svg_renderer: start paying attention to scale_factor, collision, and fonts
svg_renderer: only process line/polygon symbolizers as <path> for now
svg_renderer: group layers in inkscape capatible way - refs #1917
protect against negative image dimensions - closes #1927
support scale_denominator override in save_to_cairo_file - closes #1930
add expected (currently failing) test for #1931
fix behavior of marker-ignore-placement on lines - closes #1931
remove debugging line
Add test for translating geometries
Merge pull request #1932 from ajashton/geom-translate-test

Add test for translating geometries
fix #1933 by ensuring that only tests for valid plugins are run
add mapnik.Image.premultiplied() to query status of pixel premultiplication
silence warnings
sqlite: add more debug output
fix height clamping in image_view and grid_view - closes #1940
cpp_tests: no need for dynamic_cast
handle lacking return value handling caught by coverity