Feature #148/light duty vehicles

[JakobWeg]

Fixes #148

Changes proposed in this pull request:

• optional simulation of commercial vehicle groups (commercial Cars, alight- and heavy duty vehicles)
  via a new vehicle_group column in tech_data.csv and a [commercial_vehicles] config section, disabled by default Add the possibillity to simulate light duty vehicles #148
• new charging use case depot (private charging at a commercial vehicle's company depot),
• new mcs-methodology for heavy duty vehicles

The following steps were realized (required):

• Correct formatting with black src
• Add the description of your changes to the CHANGELOG.md in subsection with release name [Unreleased] and state the PR number with #

Also the following steps were realized if applicable:

• Write docstrings to your code
• Write test(s) for new patch of code