Finished hooking up output multi.
Use the same `write_wkt` function for writing nodes.

Creating the WKT for nodes is pretty simple, so we can do that
and just call `write_wkt` so that there's a common code path.
Merge remote-tracking branch 'MapQuest/kk_multiback' into mla_multi_backend

Conflicts:
	table.cpp
	table.hpp
remove passing around of copy values sql string buffer and use only locally