rename SED and MAKE variables to fix MSYS support
support PROJ and libSHP (MSYS+MinGW)
support FreeXL on MinGW+MSYS
fix FreeXL and ReadOSM on MinGW
build Boost on GCC and older VS
build spatialite with MinGW
fix spatialite-tools on MinGW
fix osmium on MinGW
trying to build GDAL with MinGW