Resolve Codacy issues

[schuderer]

Codacy flags a couple of issues, both in code as well as in markdown files.

Resolve the issues by trying (in order):

• resolving the problem that Codacy has found (e.g. for "Method should be a function", in base classes, use the @abc.abstractmethod decorator, if really a function, use @staticmethod, etc.),
• excluding the line from Codacy's analysis (relevant for Flask debug mode, which mllaunchpad itself warns about to only use for debugging, as well as for pyyaml's loading, where we use a descendent of the safe loader, but Codacy doesn't recognize that) -- for Bandit, use # nosec
  
• disabling rules that are not sensible for this project (last resort)

[schuderer]

Added underscore _ to the allowed file name pattern of RemarkLint.