return dict of {distnumber: name} for all dists in eppic.i file.
name will be None if failed to infer the name.
name is inferred from comment lines above the lines like dist=N.
Comments with names have a few different possible formats:
1) “; [anything] distribution: name”.
Possibly using ‘ ‘ or ‘-’ instead of ‘:’, and possibly using ‘dist’ instead of distribution.
Also, possibly have another comment afterwards, e.g. “; [anything] dist - name ; [anything]”.
2) “; [anything] — name — [anything]”,
with at least 3 ‘-’ on either side, and nonzero whitespace between the ‘-’ and the name.