Add MultiIndex to codegen. Bugfixes.

Added MultiIndex to the code generator. Can now generate lookup
functions, although the name is hardcoded for now (until this info can
be attached to the tree)

Fixed a commented out line, where annotation declarations are added to
the codegen state.

Fixed a bug where a given set of annotations could produce multiple different
combo id's. The list of members should be sorted before generating a
combo id.
Merge branch 'master' of github.com:DaMSL/K3-Core