Fixes after review of guilhem of block record patch

Short overview:
Changed a lot of variable, functions, defines and struct elements to use more readable names
More comments (mostly function and structure slot comments)

Other things:
Changed 'USE_WHOLE_KEY' to a big number to not interfer with long keys
Ensure that tail block are at least of size 'MIN_TAIL_SIZE'
Allow longer keys and key parts than before (don't limit Maria interface by HA_MAX_KEY_LENGTH)
Use ma_chsize() to write initial bitmap page
Added checking if using file with wrong block_size
Added issing types to type_names[] (for maria_chk -d)
Added maria_max_key_length()


include/maria.h:
  Changed maria_portable_size_char_ptr to portable_size_char_ptr and moved it to my_handler.h
  Removed not used variable maria_delay_rec_write.
  More comments
include/my_handler.h:
  Added portable_sizeof_char_ptr
include/myisam.h:
  Changed mi_portable_size_char_ptr to portable_size_char_ptr and moved it to my_handler.h
mysql-test/r/maria.result:
  Fix results when we now have a longer key length
mysql-test/t/maria.test:
  More tests
mysys/my_pread.c:
  Code cleanup
sql/net_serv.cc:
  Changed warning to note (as in main 5.1 tree) to avoid not critical failing tests
sql/sql_select.cc:
  Use portable_sizeof_char_ptr
storage/maria/ha_maria.cc:
  Added max_supported_key_length(), as this is not a trival function anymore
storage/maria/ha_maria.h:
  Moved max_supported_key_length(), as this is not a trival function anymore
storage/maria/ma_bitmap.c:
  Lots of new comments
  Added maria_bitmap_marker[] to mark 2 last bytes of each bitmap (for corruption detection)
  Trivial code changes (based on review comments)
storage/maria/ma_blockrec.c:
  More code comments
  Renamed _block_row() functions to _block_record()
  Trivial code changes, based on review comments
  Moved Code from maria_close() to _ma_end_block_record()
  Some function renames to make things more understandable
  DIR_ENTRY_OFFSET -> DIR_COUNT_OFFSET
  keybuff_used -> keyread_buff_used
  ma_recordpos_to_offset -> ma_recordpos_to_dir_entry
  Changed some 'rec' named variables to 'column'.
  Ensure that tail block are at least of size 'MIN_TAIL_SIZE'
storage/maria/ma_blockrec.h:
  More comments
  DIRCOUNT_SIZE -> DIR_COUNT_SIZE
  Added define for maira_bitmap_marker[]
  ma_recordpos_to_offset -> ma_recordpos_to_dir_entry
  xxx_block_row() -> xxx_block_record()
  Made _ma_read_bitmap_page() static
storage/maria/ma_check.c:
  More comments
  ma_recordpos_to_offset() -> ma_recordpos_to_dir_entry()
  DIR_ENTRY_OFFSET -> DIR_COUNT_OFFSET
  rec variables -> column variables
  recdef -> columndef
storage/maria/ma_checksum.c:
  rec -> column
  Avoid an 'if' in _ma_checksum() for the common case
storage/maria/ma_close.c:
  Moved resetting of info->dfile to ma_end_once_block_record()
storage/maria/ma_create.c:
  Some variable changes to make things more readable:
  recinfo -> columndef
  rec -> column
  rec_end -> end_column
  record_type -> datafile_type
  ma_recinfo_write() -> ma_columndef_write()
  Fixed wrong setting of 'data_file_length'; Now max_rows should be calculated correctly
  New check if too long key.
  Use ma_chsize() to write bitmap page.
storage/maria/ma_delete.c:
  keybuff_used -> keyread_buff_used
storage/maria/ma_dynrec.c:
  rec -> columndef
  rec_length -> column_length
  maria_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
  Better comment for _ma_read_rnd_dynamic_record()
storage/maria/ma_ft_eval.c:
  maria_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/maria/ma_ft_test1.c:
  maria_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/maria/ma_ft_update.c:
  keybuff_used -> keyread_buff_used
storage/maria/ma_info.c:
  More comments
storage/maria/ma_open.c:
  Added checking if using file with wrong block_size
  New checking of max_key_length
  rec -> columndef
  _ma_recinfo_write -> _ma_columndef_write
  Don't change block_size (as this is checked in ma_create())
  More comments
storage/maria/ma_packrec.c:
  Trivial code changes
  rec -> columndef
  maria_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/maria/ma_page.c:
  keybuff_used -> keyread_buff_used
storage/maria/ma_rkey.c:
  Removed not needded empty line
storage/maria/ma_rrnd.c:
  Removed not used variable
storage/maria/ma_rt_index.c:
  keybuff_used -> keyread_buff_used
storage/maria/ma_search.c:
  keybuff_used -> keyread_buff_used
  Trivial code changes
storage/maria/ma_sp_test.c:
  maria_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/maria/ma_test1.c:
  maria_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/maria/ma_test2.c:
  maria_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/maria/ma_update.c:
  Updated comment
storage/maria/ma_write.c:
  keybuff_used -> keyread_buff_used
storage/maria/maria_chk.c:
  Added missing types to type_names[]
  Removed not used variable
  rec -> columndef
  Replaced some numbers with define flags
storage/maria/maria_def.h:
  More comments
  Added 'MARIA_INDEX_MIN_OVERHEAD_SIZE'
  rec -> columndef
  keybuff_used -> keyread_buff_used
  _ma_recinfo_write -> _ma_culumndef_write
  _ma_recinfo_read -> _ma_columndef_read
  Changed 'USE_WHOLE_KEY' to a big number to not interfer with long keys
  Added maria_max_key_length()
storage/maria/maria_pack.c:
  Updated message strings
  rec -> columndef
  maria_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
  More comments
storage/myisam/ft_eval.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/ft_test1.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/mi_checksum.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/mi_create.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/mi_dynrec.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/mi_open.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/mi_packrec.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/mi_rkey.c:
  Unlock mutex also in case of error
storage/myisam/mi_test1.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/mi_test2.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/myisampack.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
storage/myisam/sp_test.c:
  mi_portable_sizeof_char_ptr -> portable_sizeof_char_ptr
support-files/magic:
  Fixed typo

include/myisam.h

@@ -55,8 +55,6 @@ extern "C" {
 #define MI_MIN_KEY_BLOCK_LENGTH	1024	/* Min key block length */
 #define MI_MAX_KEY_BLOCK_LENGTH	16384
 
-#define mi_portable_sizeof_char_ptr 8
-
 /*
   In the following macros '_keyno_' is 0 .. keys-1.
   If there can be more keys than bits in the key_map, the highest bit