Create installable artifacts

[leamas]

This series eventually produces a tarbal and xml metadata which makes it work together with https://github.com/OpenCPN/OpenCPN/pull/1457 . In short, it provides:

• A more robust handling of the windows API linkage
• An update to support relocatable data directories using latest plugin API
• Flatpak and mingw build support
• ci jobs using travis.com and/or circleci.com + appveyor.
• builds on Debian, mingw, msvc, MacOS, flatpak and fedora.

The README.md has some more details on the patches.

This should not affect the currently used packages and how they are created.

[leamas]

Here are the bits and pieces which creates a usable tarball and XML files for the installer. Rick has made a lot of documentain -- however, the README.md should work.

The CI part is probably the most work. If you want to test this path:

• You need to set up accounts on circleci and cloudsmith.
• Make sure that the cloudsmith repo is created as an opensource one, it cannot be changed later
• Request a MacOS builder on circleci. This is a manual process, but has been fast and simple.

BTW: why circleci?

• faster (25 - 100%)
• Killer feature: you can log in to failed builds using ssh, test, discover. Saves lot's of time.

Why cloudsmith:

• Multiple repos for stable, unstable etc.
• Mature adminstration tools.

[leamas]

@bdbcat: Time to close?

[bdbcat]

Closing, thanks for the code.