+ fix writing to std::stringstream

* if seeking pass the end  - grow buffer (stringstream!)
* seekp beyond current buffer size doesn't set failbit (clang/libcxx)
Merge branch 'master' of https://github.com/mapnik/mapnik
TIFF I/O

+ use generic std::istream
+ add open from char const* and size factory method
scons: fix g++ detection logic on OS X
re-enable tiff from string tests - refs #1805 - closes #1831
Merge branch 'master' of https://github.com/mapnik/mapnik
fix tiff compile against older than tiff 4.x
Merge branch 'master' of https://github.com/mapnik/mapnik
Geometry/Feature parsers -truncate 'where' message in on_error handler (currently 16 chars max)
fix compile in master after 8d5b983cb6861b since master still uses phoenix v2
Reenable Cairo and grid tests.
+ check if geometry record (WKB) is not Null before attempting to parse
+ log Null geometry case ( via @TomH )
+ fix accidental typo :)
disable compiling the c++ benchmark by default
remove expression_grammar from public api
rename css_color_grammar_def.hpp -> css_color_grammar_impl.hpp to be consistent with other headers
move expresion_grammar impl to impl header
Merge branch 'master' of https://github.com/mapnik/mapnik
rollback MAPNIK_DECL on exceptions - which breaks linking of python bindings on msvc - refs #1826