use premultiplied renderer for points/shields - closes #2117
another try to fix linking order on linux
boost threads are no longer needed
fix -pthread issue on linux - closes #2132
addLayer -> add_layer (change also coming in expr-v2 branch)
boost::array -> std::array
include <array> header for std::array
catch another addLayer -> add_layer case
adapt build to use BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
Merge branch 'master' of github.com:mapnik/mapnik into expr-v2

Conflicts:
	tests/cpp_tests/svg_renderer_tests/path_element_test.cpp
further no terminal port
fix compile with BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
fix topojson compile and centralize confix workaround
Merge pull request #2134 from mapnik/no-predefined-terminals

Use BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
geometry envelope: calculate size once
remove compile workaround for old OS X gcc since we only support c++11/clang++ now at Mapnik 3.x - refs #1835
remove workaround for boost less than 1.46 since 1.47 is now the min needed - refs #1082
remove env clone and instead just push DHAVE_LIBXML2 into main CPPDEFINES
update expected tests after #2117
minimum boost version is 1.47 - remove obsolete code handling older versions