first stab at moving mutable render request properties out of apply_to_layer
sync with master
Merge branch 'master' of github.com:mapnik/mapnik into map-request
Merge branch 'master' of github.com:mapnik/mapnik into map-request
Merge branch 'master' of github.com:mapnik/mapnik into map-request
further refine the mapnik::request object which can be passed to custom agg_renderer
Merge branch 'master' of github.com:mapnik/mapnik into map-request
Merge branch 'master' of github.com:mapnik/mapnik into map-request
fix cairo dash array rendering - closes #1740
enable cairo in the cpp tests
implement support in cairo and grid renderer for mapnik::request - refs #1737
Merge pull request #1737 from mapnik/map-request

Rendering hook to allow for passing mutable map properties via mapnik::request object