When starting the game in windowed mode, the window buffer used whatever
was on the screen before running the game. Kind of like you could see
through the window, but it doesn't update what happens behind it.
It makes it look like something is broken or non-responsive.
So clear the window opengl buffer to black.
Credit to theinvsblman for the code.
SDL1.2 branch disables key repeat when key catcher is 0.
Presumably to prevent binds from executing multiple times.
SDL2 replaced being able to disabled key repeat using SDL_EnableKeyRepeat
with a non-zero repeat value in the key event.
Setting SDL_GL_ACCELERATED_VISUAL was disabled for ioq3 SDL 1.2
for other reasons. However, it causes creating GL context to fail
if multisampling is enabled on X11 for both SDL1.2 and SDL2.
Tested using nVidia proprietary driver on Debian 7.
UI VMs expect a backspace char event, but sdl2 branch only was only sending a key event.
Revert cl_keys.c to master branch (it would cause backspace to happen twice in console).
Quiting SDL Video or Joystick subsystem implies quiting the Event subsystem in SDL2.
SDL keeps track of number of init and shutdown calls for each subsystem.
Shuting down video or joystick more or equal to number of times they're inited will lead to event shutdown.
Toggling in and out of fullscreen or running in_restart twice causes SDL event subsystem to shutdown, making input not work.
If the console is closed, IN_GobbleMotionEvents gets stuck in a loop. SDL_PeepEvents returns -1 when there is an error, but we assume non-0 means read more events.
IN_ShutdownJoystick needs to check if joystick subsystem was inited before quitting it, otherwise we may cause SDL event subsystem to shutdown.
Make 'b' variable an int so that key values more than 255 will work (not currently an issue in ioq3 afaik).
Use SDL_BUTTON_* for easier transition to SDL2.
(SDL2 doesn't have SDL_BUTTON_WHEELUP or SDL_BUTTON_WHEELDOWN, X1/X2 are different values.)
