3.x port of localized font caching and then some
fix benchmark compile
c++ style
unique_ptr for font_face_set
ignore font cache in map assignment and comparison
cleanup
add code comments to create_face
simplify code in create_face
Merge branch 'master' of github.com:mapnik/mapnik into localized-font-cache

Conflicts:
	src/build.py
Merge branch 'master' of github.com:mapnik/mapnik into localized-font-cache
rebase with master
Merge branch 'master' of github.com:mapnik/mapnik into localized-font-cache
Merge branch 'master' of github.com:mapnik/mapnik into localized-font-cache
remove state from freetype_engine - now fully static
fast, non-caching check if a font can be opened and read
per map load cache if a fonts is known as valid
remove unneeded include
only memcache local fonts if not already globally known and not already cached (avoid extra io for ttc)
c++ tests for font registration and caching on map
Merge pull request #2454 from mapnik/localized-font-cache

3.x port of localized font caching