Fix MinGW cross compiling build on Ubuntu host system.
Attempt to add CI build for Windows platform using MinGW cross compiling toolchain.
For Travis CI - fix quotation marks.
For Travis CI - try to fix installation of MinGW-W64 packages.
Somehow apt-get in Travis-CI build environment does not auto install all the dependencies.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	.travis.yml
	Rakefile