Error in database query syntax, when table aliases are used in "option_key_field" or "option_title_field" field options

In some case we need to use JOIN in database queries, that are used in "options_sql" option for field. In many cases there is a possibility, that fields, selected in "option_key_field"/"option_title_field" options will be present in more, then one table, used in JOIN. This will result in database query error.

I propose to strip table alias (if any) when building field options list.