[HL] Allow the clickable Game Menu text to be replaced by images

[Zarko Dinev]

Currently all clickable game menu text is just that.. text... It's dependent on the scripting provided with the game and it's on the mercy of the OS used. Sometimes in mods if the font outlined is missing in the Guest OS of the platform used the Game Menu clickable text will not be rendered properly. Other times just the color scheme used will make it unreadable towards the current background used.

Please allow the ability for the Game Menu text buttons to support .tga images.

I'm talking about the buttons located on the gamemenu.res file -> New Game, Load Game, Disconnect, Quit, LAN Game, Find Server, Create Server etc.

This will improve the quality of life for Half-Life mod makers.

Thanks.