WL#1218 "Triggers". Some very preliminary version of patch.

Mostly needed for Monty for him getting notion what needed for triggers 
from new .FRM format. 

Things to be done:
- Right placement of trigger's invocations
- Right handling of errors in triggers (including transaction rollback)
- Support for priviliges
- Right handling of DROP/RENAME table (hope that it will be handled automatically
  with merging of .TRG into .FRM file)
- Saving/restoring some information critical for trigger creation and replication
  with their definitions (e.g. sql_mode, creator, ...)
- Replication

Already has some known bugs so probably not for general review.

sql/sql_insert.cc

@@ -19,6 +19,8 @@
 
 #include "mysql_priv.h"
 #include "sql_acl.h"
+#include "sp_head.h"
+#include "sql_trigger.h"
 
 static int check_null_fields(THD *thd,TABLE *entry);
 #ifndef EMBEDDED_LIBRARY
@@ -299,6 +301,12 @@ int mysql_insert(THD *thd,TABLE_LIST *table_list,
 	break;
       }
     }
+
+    // FIXME: Actually we should do this before check_null_fields.
+    //        Or even go into write_record ?
+    if (table->triggers)
+      table->triggers->process_triggers(thd, TRG_EVENT_INSERT, TRG_ACTION_BEFORE);
+
 #ifndef EMBEDDED_LIBRARY
     if (lock_type == TL_WRITE_DELAYED)
     {
@@ -321,6 +329,9 @@ int mysql_insert(THD *thd,TABLE_LIST *table_list,
       id= thd->last_insert_id;
     }
     thd->row_count++;
+
+    if (table->triggers)
+      table->triggers->process_triggers(thd, TRG_EVENT_INSERT, TRG_ACTION_AFTER);
   }
 
   /*