Building for windows using Docker

[drowe67]

1. Using Danilo's fine work to allow us to build freedv-gui for windows using Docker. This is another step in automating the build process, and allows us to use Docker containers rather than a Fedora machine.

   Thanks Danilo for showing how this can be done 👍

2. Now building working Windows installers, people have tested the EXEs with good results.

3. Fixed a FIFO size bug that had broken 2020 Rx.

4. Automation script to build freedv-gui on a remote machine and upload 32 and 64 bit Windows installers to a web site in a single step.

[ghost]

That is on my wish list! Bravo

[hobbes1069]

Looks interesting! It doesn't really matter since we're just using the mingw capabilities but technically Fedora 28 is EOL.

[hogthrob]

Hi,
changing the Fedora release is a simple matter of changing FED_REL in docker-compose-win.yml to any desired number and verifying that the build instructions in the docker file fdv_win_fedora/Dockerfile are still working for this release.

[drowe67]

Thanks @hobbes1069 @hogthrob I'll try Fedora 30 on the next pass on this code. Certainly makes my life easier - one script to run for the whole build and deploy process.