Add preliminary disk swapping interface.

Works with Mednafen's disk swapping model.
Merge branch 'master' into cd-swap
Merge branch 'master' into cd-swap
Log which SwapInterval implementation is used.
start of RGUI port to Android

currently detects menu button to bring up RGUI, but GL does not draw it
yet and you cannot exit from the (invisible) RGUI menu yet
commit makefile changes
change some logs around

detect menu key from any "controller"
Set texture filtering for RGUI texture.
get touch navigation working

fix colors for GL
make seperate option list for non-consoles
allow orientation changes in RGUI

allow closing RGUI menu, need to make the key binds sane
(Android) Make function pointer engine_handle_dpad - use AMotionEven_getAxisValue
if we can use it (on Android 4.0 and up)
(Android) Define HAVE_ASYNC_POLL for Android (will likely be used for other
mobile platforms as well)
(Android) Drop this ifndef - to allow input overlay poll to still happen
(Android) Blank in input_poll_func() for HAVE_ASYNC_POLL
Make android_handle_events an implementation of input_poll function -
rely on HAVE_ASYNC_POLL whether or not input_async_poll_func or
input_poll_func is 'blanked out'
(Android) Make HAVE_ASYNC_POLL optional
(Android) Don't define HAVE_ASYNC_POLL for now
(Android) Make engine_handle_input a part of android_input_poll
(Android) Check explicitly for either LOOPER_ID_INPUT or LOOPER_ID_MAIN
in anroid_input_poll
(Android) Input autodetection - corrected RetroPad R / RetroPad L2
for WiseGroup PS2 to USB