Refactored the 'yc D:I' and 'yc D:U' commands and improved their
performance.
Removed unneeded SQL commands for setting character set etc from all
the bin/sql/*.sql and bin/sql/updates/*.sql as they duplicated
existing connection settings in 'yc D:I' and 'yc D:U'.
Also added the dropping and adding of the SQL addOrModifyColumn
procedure to 'yc D:U' so isn't needed in each update.