Additional Player resolutions with Retina support

- Added Player resolutions for the iPhone 6, iPhone 6 Plus, and that
goofy 900x1200 resolution that Apple demands for iPad preview videos in
the App Store for who knows what reason.
- Added a preprocessor directive to include unistd.h in
gmicrophone-openal.cpp on platforms other than Windows.  The reason
being that the compiler would throw an error complaining that usleep()
was undefined.
- Got a similar complaint from the compiler concerning ::getuid() in
qtlocalpeer.cpp, which went away when I added the QtLP_Private
namespace.