Build libbiosig on Windows

[cbrnr]

Currently we can build libbiosig from source only on macOS and Linux. However, we should try to get it to work on Windows as well using our build environment. Right now, this means MinGW, this should be our priority here. Since SigViewer builds with VC without any problem, in theory it should be possible to compile libbiosig with VC as well. This would be the ideal solution, because VC is the default build environment on Windows, but I doubt that it will be easy to adapt the source of libbiosig (it uses a lot of GCC extensions).

[Yida-Lin]

@cbrnr In my impression SigViewer never worked with VC on Windows? Got a ton of mistakes always. Same with libbiosig. I had multiple tries last year on both but never succeeded.

[cbrnr]

No, SigViewer does build with VC if you remove all biosig-related stuff.

[cbrnr]

Note that you need to have the VS version of Qt installed and not the MinGW one.

[tstenner]

No, SigViewer does build with VC if you remove all biosig-related stuff.

Is there a branch with a bunch of #ifdefs?

[cbrnr]

No, unfortunately we never bothered to do that. I don't have the time to look into that, but I think everything should work with MinGW64, which is now officially supported by Qt.

[tstenner]

I have a semi-official all-in-one installer for lsl and so far an xdf file visualization tool is missing.
Everything's built with Visual Studio, so if it were possible to include a minimal sigviewer that'd be great.

[cbrnr]

Removing Biosig won't be easy. I'm not happy how deeply it became integrated at some point, but I don't have the time to work on that. Changing Biosig to be compatible with VSC won't be easy either, and I don't have time for that either. If someone wants to work on that I'd be more than happy, but I doubt this is going to happen.