simplified calculate_instance; worked around some clever code; clever code is unfortunately still there...needs to be removed
Higher Priority
===============
- if the constant definition gives the wrong definition
  term, one gets a cryptic message about get_fun
- have FSet.thy to have a simple infrastructure for 
  finite sets (syntax should be \<lbrace> \<rbrace>,
  look at Set.thy how syntax is been introduced)
- Handle theorems that include Ball/Bex. Would it help 
  if we introduced separate Bex and Ball constants for 
  quotienting?
- user should be able to give quotient_respects and 
  preserves theorems in a more natural form.
- the test in the (_, Const _) needs to be fixed
Lower Priority
==============
- Maybe a quotient_definition should already require
  a proof of the respectfulness (in this way one
  already excludes non-sensical definitions)
- accept partial equvalence relations
- 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.
- wrapper that translates an an original theorem given
  a list of quotient_types as an attribute
- 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)
- use lower-case letters where appropriate in order
  to make Markus happy
- add tests for adding theorems to the various thm lists
- Check all the places where we do "handle _"
- We shouldn't use the command 'quotient' as this shadows Larry's quotient.
  Call it 'quotient_type'
- Maybe quotient and equiv theorems like the ones for
  [QuotList, QuotOption, QuotPair...] could be automatically
  proven?
- Examples: Finite multiset.
- The current syntax of the quotient_definition is
      "qconst :: qty"
      as "rconst"
  Is it possible to have the more Isabelle-like
  syntax
   
      qconst :: "qty"
      as "rconst"
  That means "qconst :: qty" is not read as a term, but
  as two entities.