Support integer literals in range expression of for loops.

## `generator`
Support integer literals in range expressions of for loops and allow variable usage in count part of write statement.  

The changes are downwards compatible and resolve #120 "Dynamic sample size in for-loops".

Changelog: changed

Adding a script for automatically deleting unused packages from the package registry. This script is triggered by a scheduled pipeline. 


Resolves !34 "Automatically remove packages for deleted branches"