Infrastructure: Bump version to 0.5.3 for publishing

Infrastructure: Bump version to 0.5.0

Bump version to 0.4.4

Bump version to 0.4.3

Infrastructure: Bump NetLogo API to 6.1 and version

Bugfix: Do not be over-eager to close the output

Bump version to 0.4.0

Remove obsolete halt documentation

Shutdown python process on halt. Fixes #8

Also, gracefully handle

- shutting down of python process
- unpexpected disconnects

Allow configuration menu to save blank entries