add deque to array alloc benchmark
support building without dlopen support

Conflicts:
	SConstruct
drop use of xml entities in text-font-features test - fixes #2590
update visual test images for #2590
markers: support restyling svg stroke and fill without limit - closes #2609 - refs mapnik/mapnik-support#27
change config_error to std::runtime_error in scale_hsla struct
consistent std::move in image data move ctor
new dot symbolizer for fast rendering of points - refs #1651 mapbox/mapnik-vector-tile#62 #2612
update warp expected image