Main Menu in the CombatMap

Added a Main Menu on the CombatMap that is displayed above the map when
open
- Currently offers buttons to close the menu, return to the main menu
and exit the application
- Button on menubar replaces the button that returns to the Main Menu

Resized and removed the labels from the buttons on the CombatMap menu
bar in preparation for rendering the buttons as icons
Initial preparation for functionality to resize and move UI elements
according to the resolution
Split rendering of text to allow for proper overlap of UI Elements,
visibility of text.