Script editor support, plugin conversion

New script editor support for plugins, plugin engine will try to use registered script editor, if none found it falls back to a generic textbox.  The codebase still needs some more cleanup, I think, but it's getting there. :smiley: 

Oh, one other thing: Using the FastScripter plugin as an embedded editor is bugged, but I can't figure out what's wrong. It screws up when entering text and doesn't appear to remember the contents when clicking OK. I can't figure out what's wrong, though, as the stock script plugin appears to work fine.

*edit:* Nuked dead code, moved map and image menus into respective plugins. The editor code is much cleaner and easier to navigate now!

*edit 2:* Spriteset and windowstyle plugins