Replace phstore flag in style by a generic hstore flag
which is also usable for points and lines.
This is useful in conjunction with the --hstore-match-only option
Keep phstore option as an alias for polygon,hstore to provide
backward compatibility for older style files.
The point processor just looks at nodes to determine the output -
we should have another one which is able to do centroids for
matching types.
Added a test case for this and factored out a bunch of common code
for setting up test databases.