shuffle blend functions
[appveyor] renabled node v0.8 [publish binary]
mention webp support in windows binaries after packaging fix https://github.com/mapnik/mapnik-packaging/commit/53577abc54a4546fa7ca313dda576e8947367a24
[travis] multi-os support
more attributes support
more image i/o tests (jpeg+tiff+webp)
Add missing test data
[appveyor] stop testing on node v0.8.x temporarily
[travis] stop testing on node v0.8.x temporarily
also testing encoding for jpeg/tiff/webp
update expected test - refs mapnik/mapnik#1313
add raster overzooming test + update visual comparisions to use mapnik.Image.compare
Testing out os timing differences.
Merge pull request #282 from mapnik/timing

Testing out os timing differences.
add missing 'invert-rgb' compositing mode
strip newlines and whitespace in XML comparison test
add test comment in relation to https://github.com/mapnik/mapnik/commit/ecc5acbdb953e172fcc652b55ed19b8b581e2146
fix conditional support for webp/jpeg/png in blending - closes #283
update mapnik SDK for both 2.3.x and 3.x
build fixes against mapnik master