remove geos plugin (moved to https://github.com/mapnik/non-core-plugins) - refs #1809
+ c++ style
+ backport image_reader from buffer/string from image-readers-c++11 branch
+ fix warnings when compiling with g++ 4.2.1 on os x
Merge branch 'master' into image-readers-c++11

Conflicts:
	bindings/python/mapnik_image.cpp
	include/mapnik/factory.hpp
	include/mapnik/image_reader.hpp
	src/image_reader.cpp
	src/jpeg_reader.cpp
	src/png_reader.cpp
 * use move semantics
 * use light weight wkb_stream wrapper to avoid locale/formatting locking