Misc GUI fixes
- connect TreeImportExport to GUI
- remove save/load tree buttons
- Invalidate menu item can invalidate whole modules
- Multitree: use HTREEITEM as map key
- Add key to (Import)ModuleThunk to easily delete from module-/thunklist, might need a little code cleanup or real constructor for the two structs
- Add hex only edit control and wrappers (beep on invalid input)