android: Log number of invalidated tiles

Change-Id: I1ebfcf48f1d9a44836b4d9bf90c04c3be27cb365
android: clean MultiTileLayer of unneeded variables/methods

Change-Id: I7750322000230448d6283107daace3d9bb5da61d
android: rerender tiles when the zoom changes

Initial implementation which needs a lots of polish. Sometimes
the app crashes (for yet unknown reasons). Sometimes a gap
between tiles is visible probably because of rounding errors.
Tile handling and releasing after zoom is quite naive for now
(just clearing all the tiles) which needs to be improved to be
more seamless.

Other changes: The responsibility of LOKitThread to handle tiles
was moved to MultiTileLayer. TileProvider now takes into account
the current zoom level when requesting tile rerendering.

Change-Id: Ic188c03bfadf3a3dd2f79b04f07668eb63b705fb
android: remove tiles delayed by one redraw call

Change-Id: I5ab5e4a0ba9cdf3f3115c4913b4cf04e7f062755
android: change pageSize to pageRect (Fennec import)

Change-Id: Ia3958b174e7190171cbd006550e47677a1ba0966
android: remove unused screenSize (Fennec import)

Change-Id: I0b8d1b29ab3219bc75de6c087e410523c18dbeef
android: PanZoomControler updates from Fennec

Change-Id: Ic338221ced6133771af8f46ae4a257e043a1709f