move symbolizer to json into core
symbolizer json grammar (needs more work)
c++11
fix svg_renderer
Merge branch 'master' of github.com:mapnik/mapnik into expr-v2
generic ```to_integral``` helper function (convert strongly typed enumeration values to underlying type)
convert json value into symbolizer_base::value_type
register target type for symbolizer properties
symbolizers: set_property helper
Merge branch 'expr-v2' of github.com:mapnik/mapnik into expr-v2
avoid signed comparison warning in symbolizer test
Revert "don't set -stdlib in CXXGLAGS"

This reverts commit 62c06eabcc18cfb8a63ee764ccbe4d86bb90eefc.
Merge remote-tracking branch 'upstream/expr-v2' into jmh-group-symbolizer

Conflicts:
	src/symbolizer_keys.cpp
Factored out placement checking.

Placement checking, that is using the layout to figure out where
the bboxes of text and markers go, was done in `placement_finder`,
but this extracts it out (for point placement) into a separate
class so it can be re-used when placement is more complex than
just whether the current feature "fits" or not.
Merge remote-tracking branch 'origin/jmh-group-symbolizer' into jmh-group-symbolizer

Conflicts:
	src/symbolizer_keys.cpp
Merge pull request #1 from MapQuest/mla-group-symbolizer

Factored out placement checking