* moved filter constants back to d2enum
* moving key and mouse button enums into d2enum
* moving render type enum into d2enum
* moving input even priority enums into d2enum
* moving terminal enums into d2enum
* lint fixes for the game.go
* lint fixes for the gui_testing.go
* lint fixes for the blizzard_intro.go, map_engine_testing.go and select_hero_class.go
* added package comment for the d2gamescreen package
* fixes after merge
* more lint fixes for the d2core/d2term
* lint fixes for the escape_menu.go
* fixed lint issues of credits screen
* more lint fixes for the d2gamescreen
* lint fixes for the main menu of d2game/d2gamescreen package
* lint fixes for the main menu and map engine testing of d2game/d2gamescreen package
* more lint fixes for the main menu of d2game/d2gamescreen package
* lint fixes for the character select screen of d2game/d2gamescreen package
