Merge pull request #210 from dariomanesku/master

Imgui updates.
Removed psapi.h from non-windows builds.
Fix.
added view id checks
Merge pull request #212 from attilaz/checks

added view id checks
SDL2: Added gamepad support.
Cleanup.
Merge branch 'master' of github.com:bkaradzic/bgfx
Cleanup.
Fixed RenderDoc define on Linux.
Fixed compute program destruction.
Included bgfx_shader.sh to bgfx_compute.sh.
Fixed issue #202.
Added XInput support.
SDL: Added connect/disconnect gamepad events.
Added gamecontrollerdb.
Implemented missing casts.
Cleanup.
Merge branch 'master' of github.com:bkaradzic/bgfx
Added 24-nbody compute shader example.