Highest Priority
================
- give examples for the new quantifier translations in regularization
  (quotient_term.ML)
Higher Priority
===============
- If the constant definition gives the wrong definition
  term, one gets a cryptic message about absrep_fun
- Handle theorems that include Ball/Bex.
  Workaround: Unfolding Ball_def/Bex_def is enough to lift,
    in some cases regularization is harder though.
- The user should be able to give quotient_respects and
  preserves theorems in a more natural form.
Lower Priority
==============
- the quot_lifted attribute should rename variables so they do not
  suggest that they talk about raw terms.
- think about what happens if things go wrong (like
  theorem cannot be lifted) / proper diagnostic 
  messages for the user
- inductions from the datatype package have a strange
  order of quantifiers in assumptions.
- find clean ways how to write down the "mathematical"
  procedure for a possible submission (Peter submitted 
  his work only to TPHOLs 2005...we would have to go
  maybe for the Journal of Formalised Mathematics)
- add tests for adding theorems to the various thm lists
- Maybe quotient and equiv theorems like the ones for
  [QuotList, QuotOption, QuotPair...] could be automatically
  proven?
- Examples: Finite multiset.