Hextile live wallpaper

This is a futuristic-looking interactive live wallpaper.

To-do list:

* Self-illumination in edge shading mode.

* Periodic animations.

* (building on periodic animations) daydream support.

* Look again at scrolling. It looks hard to do correctly on some Launchers (Samsung Touchwiz, HTC). Some other wallpapers emulate it, but don't work for direct page selection.

Version history:

v1.0: initial release.

v1.1: configurable colours.

v1.2: correct black background when freshly installed (config problem).

v1.3: implement more suggestions and fix bugs: lockscreen rotation fixed, allow disabling of highlights and shading, center tile layout, fix colours on older devices.

v1.4: implement another suggestion: option to colour only gaps between tiles. also fix slight height padding layout problem.

v1.5: implement another suggestion: option to scroll with homescreen position. This will only work on devices with launchers which support scrolling wallpapers (notably, not Samsung TouchWiz).

v1.6: back out scrolling support. it might return in the future, but for now it was a little under baked.

v1.7: correct crash in touch handling at same time as screen rotation.