Remote android button handling (again). do the press/unpress more like other targets (i.e correctly). The DPAD is special in that the press/unpress happens too quickly, so always post it with the BUTTON_REL. This means all keymaps using the dpad need to remember it will always have a BUTTON_REL (which also means they cant do repeats, which are impossible anyway).
Also make the back button go back to the OS home from the rockbox main menu
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28475 a1c6a512-1295-4272-9138-f99709370657