benchmark: add tests for expression grammar parsing - refs #1706
scons: remove uneeded BOOST_SPIRIT_THREADSAFE flag - closes #1706
iwyu
+ add missing EOL
add testcase for broken premultiplied alpha in resampling - refs #1489 and mapbox/tilemill#1888
fix raster resampling bug - closes #1489 and fixes mapbox/tilemill#1888
Merge remote-tracking branch 'origin/master'
support reading raster-colorizer properties off of raster symbolizer as well as in standalone child element
Merge remote-tracking branch 'origin/master'
+ cleanup style..
+ fix return value policy
+ implement Map::styles method returning StyleRange object

  ```
  import mapnik
  m = mapnik.Map(256,256)
  ...
  for style in m.styles:
      print style
  ```
+ provide both symbols and copy_symbols methods
+ symbolizers: add hash impl
rename simplify-tolerance -> simplify to match clip/smooth params
throw if we cannot detect image extension instead of failing silently
ensure agg headers are always installed