Features/continuous integration

[roryprimrose]

I've converted the project to the SDK style csproj and added a GitHub Actions yml build script.

To use this you need to enable Actions and point it to .github/workflows/ci.yml. Any build will produce a zip package against the action. Any build against the master branch or version tag will also create a GitHub release with the package attached.

To create a release you need to:

• Tag any (master) branch commit with a SemVer release tag as vMajor.Minor.Patch (note the v prefix)
• Push the tag

Master branch builds without a tag will be built as Major.Minor.Patch-BetaXXXX. With a tag it will build the package as Major.Minor.Patch. The script will create the GitHub release and publish the compiled (zipped) app to the release only for master or tag builds.

For example, my fork did this for a build. In this case I disabled the branch filter to create a release on the feature branch.

So basically all you have to do is create a tag and push it. Job done :)

One potential issue is that the official GitVersion action does seems to have some issues sometime. See https://github.com/GitTools/actions/issues/76. Current workaround is to just kick the build again.

Closes #44 Closes #48