Don't pass null to the mysql error functions. Even though the PHP
documentation states a null value can be passed, a warning message is
given if it is passed.
* UTF8 Conversion: Also convert existing data to make sure all records are utf8
* Add from charset for utf8 conversion (default is autodetect)
* Allow a dry run of utf8 conversion and show which queries would be performed
* Convert the table first before manually converting the columns
Languages other than english should manually set the LC_NUMERIC locale to en_US otherwise floats may contain commas instead of decimal points (#634)