make inflated image for blurring opt-in via 'image-filters-inflate' option - refs #2165

Conflicts:
	src/agg/agg_renderer.cpp
fixes after merge
support scale_factor in geometry-transform translate and scale - refs #1926
update more tests after e49f63730e7 - refs #1926
avoid double application of scale_factor - refs #1926
fix static linking of gdal/ogr plugins on linux - refs mapnik/mapnik-packaging#123
fix postgis plugin linking when statically linking on linux - refs mapnik/mapnik-packaging#123
prevent double-free in mapnik::projection

A double-free can happen when init_proj4 is called outside of the
constructor (for projections with defer_proj_init=true) and when that
call fails. In this case proj_ctx_ is not set to NULL and then freed
again in the destructor. Set to null to avoid second pj_ctx_free call.

See #2170
testcase for #2170
silence debug print
Make sure status() returns a message also on bad connection

Closes #2173.
Do not attempt to PQclear a null PQresult*
std::make_unique