Proposal for tracking template metadata for each generated class

The goal is to allow simple retrospective refactoring of patterns. This is in principle possible by matching on equivalence axioms, it will be simpler to do this by exposing the template filler values.

Basic structure:

```
Annotations:
applies-design-pattern $PATTERN_NAME,
var1 FILLER1,
...
varN FILLERn

```

`$PATTERN_NAME` should be an IRI rather than a literal. Currently the pattern name field is the basename of the file. A good choice of IRI would be `$OBO/lc($idspace)/patterns/$basename`. Should we encourage `lc($idspace)/patterns/$basename` in the pattern_name field?

This could also form the base for the vars, e.g. `$OBO/lc($idspace)/patterns/$basename/$varX`

The fillers would be the IRI values of the actual filler.