Fixed bug 2868 - SDL_FillRect can crash if surface's clip-rect is out-of-bounds

Thanks to John Skaller for the research into this, and for the fix!

Emscripten: Fixed out of range joystick device index after joystick disconnect.

After disconnecting a joystick the remaining kept their original device index.
This was not correct because the device index must be a number between 0 and
SDL_NumJoysticks(). It was fixed with ideas from SDL's joystick implementation
for Android. Some range checks were removed as the caller already checks them.

Emscripten: Fixed sending button and motion events for not opened joysticks.

SDL_SYS_JoystickUpdate() was implemented incorrectly. For every call to it all
attached joysticks were checked. But actually only the given SDL_Joystick should
be checked then. This allowed sending broken events for attached but not opened
joysticks. It also checked the opened joysticks more often than actually needed.

Fixed naming conventions in some SDL_assert types, added compat #defines.

Fixes Bugzilla #1997.

Mac OS X: Better way to stop duplicate joystick reports (thanks, Kyungdahm!).

Fixes Bugzilla #2822.

Windows: Added a FIXME.

Windows: Free the argv we allocated for console_wmain().

Windows: Added a FIXME.

Windows: Make a distinction between ANSI mainline and UTF-8 mainline.

Windows: Support unicode arguments for console applications (thanks, Jorgen!).

Fixes Bugzilla #2864.