Add attribute text-margin in place of minimum-distance.
Handle text-margin, repeat-distance, and backward compatible minimum-distance in placement_finder. Update visual tests.
Disallow use of minimum-distance with either repeat-distance or text-margin.
Added test case for winding order of polygon rings. See mapnik/mapnik#2371 and mapbox/tilemill#2110.
Added test case for winding order of polygon rings. See mapnik/mapnik#2371 and mapbox/tilemill#2110.
Merge branch 'master' of https://github.com/IvanSanchez/mapnik

Conflicts:
	tests/visual_tests/images/polygon-winding-order-300-300-1.0-agg-reference.png
	tests/visual_tests/images/polygon-winding-order-300-300-1.0-cairo-reference.png
	tests/visual_tests/images/polygon-winding-order-300-300-2.0-agg-reference.png
	tests/visual_tests/images/polygon-winding-order-300-300-2.0-cairo-reference.png
Update visual test repeat-labels-1 to test minimum-distance functionality.
Minor improvement to repeat handling in collision detector.
expressions - implement unary and binary function expression nodes
(sample functions: exp, pow, sin, cos, min, max, tan, atan)
expressions - refactor function calls into separate compilation unit
expressions - add 'abs' function
ogr: also accept 'inline' arg like geojson/topojson/csv plugins
Add from_geojson test that validates current behavior - refs #2390
respect int return type for WebPValidateConfig
simplify expression handling in marker_helpers
add support for windows unicode paths in rapidxml loader

Conflicts:
	src/rapidxml_loader.cpp
Add visual test
fix gdal compile with msvs 2013 - closes #2257
expression_string : implement function call support
avoid creating expression_string(str) visitor objects recursively