Fix a lot of bugs in the PC editor

- Alchemy dialog had black text on dark background
- Buttons didn't depress when clicked
- Edit XP button just said "Edit"
- Two menuitems in Special Edit menu had been left with default names
- Callbacks in Special Edit and Free Extras menu weren't correctly assigned
- Edit XP dialog put the XP to next level in the wrong place
- Fixed alchemy dialog LED naming

Supporting changes in the dialog engine:
- Getting or setting control text as a number now uses the long long type to allow maximal precision
- When adding a label to a button, the dialog's default text colour is used instead of the button's text colour if the dialog's background is dark

osx/pcedit/pc.main.cpp

@@ -470,7 +470,6 @@ void handle_item_menu(int item_hit)
 	store_i = item_list[item_hit];
 	store_i.ident = true;
 	give_to_pc(current_active_pc,store_i,false);
-	draw_items(1);
 }
 
 //void set_cursor(CursHandle which_curs)