Add support for all CodeMaat analysis formats

[phanlezz]

... or add a disclaimer to readme and documentation

Description

At the moment we only support the "coupling" mode of CodeMaat. This is not explicitly stated in the readme (/documentation) of the importer, just implicitly in the suggested command line call of CodeMaat.

The other metrics, that are available from Code Maat can't be imported correctly via the CodeMaatImporter (because they are not edge-metrics and reference a null node). They can be imported via the general CSVImporter.

Development notes (optional Task Breakdown)

• [ ] Change the CodeMaat Importer to be able to handle the other more general metrics that the tool produces or
• [ ] Change the readme and documentation to advise the users to use either the CodeMaat importer or the CSVImporter depending on their use case

documentation = gh-pages

[ce-bo]

Are the edge metrics combined with "normal" metrics in one codemaat file? If so, let's support importing both with the Importer. Otherwise I would like the normal metrics to be imported by the CSVImporter and rename the Codemaat Importer to "CodemaatEdgeMetricsImporter" or similar to not duplicate logic importing a csv file.