Updated android manifest to support full sensor-based rotation

Updated graphics to 1080p

Updated build.gradle to pull in gdx-tools

Updated desktop/html launchers to use 16:9 aspect ratio

Added Platform interface and implementations for Generic and Android platforms, allowing platform-specific code to be executed from the main game class.

Modified background image draw routine for Curling mode to rotate image 90 degrees whenever a device is being used in portrait mode (based on width being smaller than height)

Added code to resize() in main game to properly adjust cameras when switching orientation on Android.

Added DEBUG variable and code sections specific to portrait-oriented 55" screen's media player.  The media player does not support portrait apps, even though android manifest says to use portrait, so the DEBUG sections modify the game's gravity to move in the x direction, and add a virtual "button" in the bottom-left corner (in portrait orientation) to toggle between ball and curling modes.