Add MinGW/MinGW64 build support

[lanurmi]

I have working builds for the original MinGW and for MinGW64(32bit and 64bit exe's). Lot's of warnings, but the exe's seem to work fine. For the MinGW target I build using the cmake MSYS Makefiles target. For the mingw64 I used "MinGW Makefiles" and use the sezero_20100212 tool chains. To get static MinGW64 builds add ' -DCMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS:STRING="-static-libgcc" ' to the cmake command line.

diff's attached based on the efte-1.1 source zip from sourceforge

Reported by: winds350

Original Ticket: efte/feature-requests/51

[lanurmi]

diffs to add support for mingw builds, 32bit only

Original comment by: winds350

[lanurmi]

Combined diffs for mingw builds, 32bit and 64bit

Original comment by: winds350