- avoids breakage on fonts lacking an `X` glyph (#2506)
- avoids needing to create and mutate a temporary glyph (#2516)
- lots of minor visual changes - mostly improvements notably more correct collision boxes for lines with tall glyphs
- Implementation by @herm for GSOC 2012 (http://mapnik.org/news/2012/10/06/gsoc2012-status9/)
- C++11 port, improvements, optimizations by @artemp
- Testing and integration with master by @springmeyer
- Thank you to all the support from @behdad along the way
- Thanks for help testing @toton6868, @stephankn, @nirvn, @mfrasca, @simonsonc and many others
Refs: #2073,#2070,#2038,#2037,#1953,#1820,#1819,#1714,#1634,#1547,#1532,#1319,#1208,#1154,#1146
