Add linter, unit tests and automated build (AppVeyor, Travis)

[HyperBrain]

The following topics should be resolved

• [x] TSLint
• [x] AppVeyor ~~Travis~~ Not important right now as AppVeyor already tests everything
• [x] Unit tests
• [ ] Coverage / Coveralls

[HyperBrain]

Coverage seems to be a bit complicated, especially to use nyc with the vscode extension testrunner. The problem is, that the testrunner spawns a vscode that runs the units under testing separately, so that nyc cannot do the instrumentation properly. According to multiple sources the only way to get this running is to write a custom testrunner...