Make the build script support Windows and BSD

[flanfly]

This extends the build script to use the cmake crate to build the native extension. On Windows it will be build with MSVC. The PR also gets rid of the build_lib.sh and adds DOtherSide as git submodule.

[White-Oak]

@flanfly This is incredible!

Could it be, that the build failing due to the old gcc on CI? It is 4.8 there.

[flanfly]

I copied half of the code off the qmlrs project, so kudos to them. DOtherSide seems to require gcc 4.9 now. The .travis file should work now.

[White-Oak]

@flanfly if this is ready for merging, I can merge it.

Thanks for all the work.

[flanfly]

Ready