Hypernymy changes

[simongray]

I moved the invalid adjective hypernymy cases over to the new dns:crossPoSHypernym relation, but simply left the ~500 cases that weren't adjectives out of the WN-LMF export (see #146).

These remaining wn:hypernym relations should be fixed so that they reference synsets of the same part-of-speech, possibly manually, but let's explore a semi-automatic way of doing it too; perhaps the amount needing manual input can be reduced.