Merge pull request #2330 from MapQuest/jh-min-distance-test

Test case for minimum distance
remove invalid csv line
fix handling of all sym enums as expressions - fixes tests from #2328
add divide, linear-dodge and linear-burn blending modes (needs testing)
travis: upgrade harfbuzz to 0.9.34
scons: ensure cairo_renderer.cpp is built farther in the stack away from expression_grammar.cpp
travis: debug broken clang++ build with harfbuzz
travis: try full path to clang++ to work around broken libtool/ linking of libharfbuzz-icu
finish python bindings + tests for #1448 and #1432
remove obsolete wrap-character option for text symbolizer - closes #2333
use std::unordered_map in non-perf critical code
iwyu
use std::sort over boost::sort
fix std::sort and std::lower_bound usage
include cleanups where we used to use boost
drop unnessary use of boost in transform_processor.hpp
travis: drop jobs slightly given recent killed processes
default to global alignment for polygon patterns - refs #2325
visual tests - keep default debug severity levels
re-enable glyph_info caching - refs #2326, #2265, #2334