provide a all-dictionary quality assurence helper

[humenda]

For mass-importing dictionaries, it would be helpful to provide a mechanism to do quality assurance over a whole set of dictionaries. There should be two flavours: one should just check and validate all dictionaries below the current directory, while another might use make need-update to fetch release-worthy dictionaries first.

The following needs to be done:

• make qa: for programmatic usage, scripts should always output the same kind of error message format, i.e. "Warning:" and "Error:".

• parallelisable way of running qa on all dictionaries + the possibility to agregate results

• nice output like:

  50 dictionaries checked.
  Without issues: …
  Issues
  ------
  
  la1-la2: (multilineoutput)
  … and more of these dictionary issues
  

It is tempting to implement this in python, but it might be also desirable to have make qa as a make rule to benefit from Make's parallelism and for extensibility reasons.

[bansp]

This is a very good idea, not only for mass import, but simply to ensure coherence across so many databases, after any project-wide modification. Let me cross-reference my ticket from freedict/fd-dictionaries#64, because both these tickets seem to share a similar spirit.