Wrap ChamplainTileCache

	* champlain/champlainmm.h: Add tile-cache.h.
	* champlain/champlainmm/.gitignore: Ignore tile-cache.*.
	* champlain/src/champlain_vfuncs.defs: Add ChamplainTileCache
	virtual functions.
	* champlain/src/filelist.am: Add tile-cache.hg.
	* champlain/src/tile-cache.[ccg|hg]: New files.
	* tools/extradefs/generate_extra_defs_libchamplain.cc: Add
	CHAMPLAIN_TYPE_TILE_CACHE.