Wrap ChamplainTileSource (partially)

	* champlain/champlainmm.h: Add tile-source.h.
	* champlain/champlainmm/.gitignore: Ignore tile-source.*.
	* champlain/src/champlain_signals.defs: Add ChamplainTileSource
	properties.
	* champlain/src/filelist.am: Add tile-source.hg.
	* champlain/src/tile-source.[ccg|hg]: New files.
	* tools/extradefs/generate_extra_defs_libchamplain.cc: Add
	CHAMPLAIN_TYPE_TILE_SOURCE.