Add missing ignore of osm_timestamp in tagtransform_c_filter_rel_member_tags()

When reading a .osm or .o5m instead of .osm.pbf file, this caused osm2pgsql to
generate ways included in relations in planet_osm_polygons in addition to the
relation.
Get changeset attribute from .osm file, to align with .osm.pbf
Merge pull request #136 from jocelynj/osm-fixes

Unwanted way in planet_osm_polygon with test .osm
fix header guard typos and add missing ones
Add additional generated files to .gitignore.
Allow maintainer mode to be disabled (debian build scripts do this).
Add ZLIB_CFLAGS to CFLAGS.
Add file config.h.in~ to .gitignore.
Fix hyphen-used-as-minus-sign lintian warnings by escaping -.

From Debian patch from Bas Couwenberg <sebastic@xs4all.nl>.
Fix spelling-error-in-manpage by using 'allows one to'.

Author: Bas Couwenberg <sebastic@xs4all.nl> via Debian patch.