Determining the proper value of GL_RGBA8 is now determined by the extensions GL_OES_required_internalformat and GL_OES_rgb8_rgba8 since it is used by textures (GL_OES_required_internalformat) but also by framebuffers (GL_OES_rgb8_rgba8)
Implemented Sys_IsWindowVisible
Modified Sys_Milliseconds to do direct calculation of time instead of function calls.
Implemented SCREEN_EVENT_POINTER and SCREEN_EVENT_KEYBOARD screen events.
Updated NAVIGATOR_EXIT event so that the navigator force-close timeout is extended until the game finishes cleaning up
Implemented NAVIGATOR_BACK for opening and closing the console dropdown.
Removed Sys_ConsoleInput from Sys_GenerateEvents since it would never be used.