Improving the src/morphology/stems files

* Are the words in the correct file? (an adverb may pop up on the noun file: move it to adverbs.lexc)
* Do the words have the correct stem? Fix it
* Do the words have the correct continuation lexicon?

!!!Derivation

Regular derivation we do in the affixes/ files.

If all verbs may be turned into nouns by adding -ing, then do something along these lines:

{{{
LEXICON Verbs
bark vmorph ;
kick vmorph ;
sing vmorph ;

LEXION vmorph
+V+Inf # ;
+V+Prs+Sg3:%>s # ;
+V+Der/ing:%>ing nmorph ; ! <=== here we derive

LEXICON nmorph
+N+Sg: # ;
+N+Pl:%>s #;
}}}

In addition to that, the lexicon Nouns may also contain an
occational lexicalised noun like ''shopping''.