Change CHARSET_INFO character set and collaction names to LEX_CSTRING

This change removed 68 explict strlen() calls from the code.

The following renames was done to ensure we don't use the old names
when merging code from earlier releases, as using the new variables
for print function could result in crashes:
- charset->csname renamed to charset->cs_name
- charset->name renamed to charset->coll_name

Almost everything where mechanical changes except:
- Changed to use the new Protocol::store(LEX_CSTRING..) when possible
- Changed to use field->store(LEX_CSTRING*, CHARSET_INFO*) when possible
- Changed to use String->append(LEX_CSTRING&) when possible

Other things:
- There where compiler issues with ensuring that all character set names
  points to the same string: gcc doesn't allow one to use integer constants
  when defining global structures (constant char * pointers works fine).
  To get around this, I declared defines for each character set name
  length.

sql/sql_string.h

@@ -183,7 +183,7 @@ public:
   }
   bool same_encoding(const Charset &other) const
   {
-    return !strcmp(m_charset->csname, other.m_charset->csname);
+    return my_charset_same(m_charset, other.m_charset);
   }
   /*
     Collation name without the character set name.
@@ -936,7 +936,7 @@ public:
   {
     return
       append('_')   ||
-      append(str->charset()->csname, strlen(str->charset()->csname)) ||
+      append(str->charset()->cs_name) ||
       append(STRING_WITH_LEN(" 0x")) ||
       append_hex(str->ptr(), (uint32) str->length());
   }