Remove generic class Map
BoundingBox: Add ChamplainBoundingBox wrapper

	* bounding-box.{hg,ccg}: Wrap BoundingBox symbols.
	* generate_extra_defs_libchamplain.cc: Add
	CHAMPLAIN_TYPE_BOUNDING_BOX.
	* convert_libchamplain.m4: Add BoundingBox& to
	ChamplainBoundingBox* conversion.