Stop snaut from crashing when no valid words in one of the lists
Stop snaut from crashing when no valid words in one of the lists

Snaut was crashing when the matrix of similarities was requested but no
words in one of the lists were present in the space. Now presence of the
words is checked before calling semspaces.matrix_distances(...) method
and page with error is returned.

pmandera/snaut,pmandera/snaut,pmandera/snaut