Changed exit status of program to successful.
Added new file main_menu.cpp to CataclysmWin.cbp
Main menu tweaks, hjkl readded to navigate, changed c_blue to c_white for readabililty.

Centerd bionic screen.
Added missing brackets.
Make diffuse mongroups use rl_dist() for distance calculation so they can tile.
Center forest monsgroups in the overmap.
Added 'Dark Days Ahead' to app window, will be adding version numbers when applicable.