Editors revamp

In this commit I totally revamped Editor suite. I changed EditorWindow
from normal form to MDI holder and content editors are now loaded as MDI
childs of EditorWindow (before they was simply tabbed). And some more
changes:
- Replaced LuaInterface by its updated fork called NLua
- Replaced old Lua 5.1 with latest Lua 5.2 version
- Finished scripting editor (added possibility of creating new
directories and new scripts directly from script editor)
- Cleaned editor suite source code (removed all content editor classes
and moved content of them to MDI forms for each editor)
- Replaced weird method of destroying target app with ErrorHandler from
object binding (destroy class) to delegate.