parse comp-op property as enumeration_wrapper or expression_str
more generic expressions in enum
support expressions in halo-comp-op symbolizer property
support expressions in stroke-linejoin and stroke-linecap properties
ENUM_FROM_STRING macro to keep things tidy and scalable
consistent namings
Made save_to_stream function available outside of library
throw on symbolizer property parsing failure
Merge branch 'master' of git://github.com/romanustinov9/mapnik into romanustinov9-master
Merge branch 'romanustinov9-master'
throw config_error, cleanup
make ```simplify_algorithm``` an expression
fix name
set_symbolizer_property : specialization for transform_type
update point_placement_enum, gamma_method_enum, line_rasterizer_enum parsing, gamma-method
markers_symbolizer properties update
perf/image_scaling: avoid unnessary clearing of target image which will already be zero-initialized
symbolizer properties : image_transform, cleanups
c++ style : pre-increment
initial implementation to pre-evaluate symbolizer properties where possible
FIXME: generic version needs needs help type deduction
[travis] drop to 2 JOBS / display cpu and free memory