- The table_priv column of table_privs table was altered to a enum type
   with fewer enums causing the SHOW/CREATE VIEW grants to be truncated.
 - Improved comments and moved all declarations for table_privs, column_privs
   and proc_privs to one section for each table making it easy to see hat alterations
   are performed on each table
 - Reduced the number of ALTER's slightly, but as this is an upgrade script we need
   to take all possibilites into account.