Getting rid of OIS

[volca02]

Getting rid of OIS

[volca02]

This also opens doors to multiplatform filesystem access (home directory, save directory...) and timers (for frame limiters, etc.)

[volca02]

Example: https://github.com/TTimo/es_core/blob/39107b27fca754b81fb364dedf8b8d33de0c18f6/main.cpp#L121

[volca02]

I also propose this: if there is video resolution setting in opde.cfg, it will get used, otherwise we'll try to find the display resolution from SDL (SDL_GetDesktopDisplayMode). If display id is specified, it gets verified v.s. SDL_GetNumVideoDisplays and if it fits, it is used instead of 0.

[volca02]

Creating branch volca/sdl2.0 for this transition, I'll try to implement this and see how it goes. I hope to resolve some long-standing issues.

[volca02]

This is pretty much done, aside from yet-unseen and undiscovered bugs introduced by the transition.
I'll merge it to master soon.

[volca02]

Merged to master.