Revamp "Copy table" dialog

From time to time dialogs need some usability refactoring. So happened with the good old Copy table dialog in HeidiSQL. New features:
- Select specific indexes or foreign keys to be created in the new table
- An editor for a WHERE clause, for cases in which you only need a subset of the original row data in the target table
- A menu for recently used WHERE clauses, so you don't need to keep them all in mind
- Prompts for overwriting if the new table exists



Thanks to Daniel for ideas and feature request number 2,000.