Updates precompiled win32 SDL 2.0.3 libs to fix the system beep sound whenever an Alt hotkey is used, patch applied from https://bugzilla.libsdl.org/show_bug.cgi?id=2669
Cleans up handling of SDL2 text input events, no behavior change expected.
Implements SDL2 text editing handler for input fields, this is for IME support, so users entering CJK text can see what they're composing before committing it. Should have no effect on SDL1 or normal text input.