Based on contributed patch from Martin Friebe, CLA from 2007-02-24.

The parser lacked support for field sizes after signed long,
when it should extend to 2**32-1.

Now, we correct that limitation, and also make the error handling
consistent for casts.


mysql-test/r/type_blob.result:
  Verify that blobs may be created with the size that is already
  documented.
  
  Additionally, test the limits of several other types.
mysql-test/t/type_blob.test:
  Verify that blobs may be created with the size that is already
  documented.
  
  Additionally, test the limits of several other types.
sql/field.cc:
  atoi() insufficient to gauge the length of some fields.  Change
  it to strtoul().
sql/item_create.cc:
  atoi() insufficient to gauge the length of some fields.  Change
  it to strtoul().
  
  If a casted length is too long, raise an error.
sql/share/errmsg.txt:
  Change ER_TOO_BIG_FIELDLENGTH so that it can accept sizes larger
  than 2**15 -- instead, 2**32.
sql/sql_yacc.yy:
  Make lengths take, in addition to NUM, LONG_NUM, ULONGLONG_NUM,
  and DECIMAL_NUM.
sql/unireg.h:
  Define new constant.