Dedicated module for pysiral scripts with entry points

[shendric]

The current processors scripts are located in the /bin subfolder, which is included in a release. This solution is functional, however outdated and cumbersome for profiling and operational use and not testable.

The targeted improvement includes moving the current scripts in /bin to a dedicated module scripts. Executable to access these scripts (L1P, L2, L2P, L3, L4?) should be generated by corresponding entry points in the setup.py.

Actions:

• Move current code in /bin/*.py to scripts.py
• Add entry points in setup.py
• Test argparse capability
• Move standard command line args from config.py to scripts.py
• Add unittest capability