fix miniz visibility with -fvisibility=hidden
try testing against boost 1.48 again - refs #2469 #2471
disable minor failing params/value_null test for now - refs #2471
travis: use harfbuzz from fontforge ppa
add wrap-character support to Layout node of TextSymbolizer
min compiler is g++ 4.8 - refs #2486
Merge pull request #2485 from mapycz/fix-text-layout-wrap-char

add wrap-character support to Layout node of TextSymbolizer
Revert "min compiler is g++ 4.8 - refs #2486"

This reverts commit 612b4a020788832b2f4a5d5b4f20a7278bc3805f.
min compiler is g++ 4.8 - refs #2486
c++ style
make vertex_cache noncopyable
remove unneeded boost/version.hpp
fix compile on windows of font_feature_settings.cpp - refs #2489
remove std::function usage in text_properties
Update group symbolizer collision to use margin instead of minimum-distance. Add test case.
Add test case expected results.
Merge pull request #2490 from MapQuest/group-margin

Use margin attribute in group symbolizer
c++ style / delay std::string creation in xml loading
fix unsafe return of temporary - closes #2493
warn if fontset not found and load_map is not in strict mode - closes #1791