Fix script for merging tags

[flayed1]

Determine why the converted tagmap contains tagsets smaller than the minimum size parameter set in conversion.
Check every step of tagmap generation.

DoD:

• bug found
• and fixed
  XOR
• explanation why smaller tagsets exist & proof that there's no bug

Future:

• implement some working algorithm

[MateuszOlko]

There were couple of bugs. Most of them is fixed. One left. Discussion is needed on how to solve it, because it is mistake in algorithm.
Working on branch: https://github.com/spacy-pl/utils/tree/analysis/finding_bug_in_conversion