error handling fixed
fetch_lengths made to work differently in embedded and client cases


include/mysql.h:
  removed 'embedded' error containers - they're unnecessary now
  added declarations for fetch_lengths to be 'virtual'
include/sql_common.h:
  fetch_lengths declaration removed
libmysql/libmysql.c:
  implementations for fetch_lengths to be 'virtual' added
libmysqld/lib_sql.cc:
  error informations now is moved from thd->net to mysql-net
libmysqld/libmysqld.c:
  error data is in mysql->net now
sql-common/client.c:
  we have to return old fetch_lengths implementation for 'client' case
sql/protocol.cc:
  handling of sqlstate for embedded library added