in a series of tests on available examples, lightweight polymorphism
encoding techniques combined with a more agressive generation of
monomorphic instances (via Discriminate) show better results than
our earlier defaults.

In the same commit:
- remove Encoding_explicit (unsound), Encoding_decoexp (too naive),
  and Encoding_instantiate (subsumed by Discriminate)
- rename Encoding_decorate to Encoding_tags_full and Encoding_guard
  to Encoding_guards_full
- move Encoding_guards_full specific functions from Libencoding to
  Encoding_guards_full
- do not apply type protection in "encoding_tptp" and remove
  Protect_finite which is not needed anymore.

Util now is a small module containing misc functions.

+ create AUTHORS file
+ fix the linking exception in LICENSE
+ update the "About" in IDE
+ remove the trailing whitespace
+ inflate my scores at Ohloh

   - add functions to Hashtbl.S
   - without ocaml 3.12 its not possible to do that for Hashtbl without
     copying the signature
   - "open Stdlib" hides the polymorphic hashtbl, perhaps a good idea
     since that avoid errors.

 (metas, debug flags, transformations, formats) except for label.

This description is used in --list-*. The description can use any of
the formatting markup of Format "@ " "@[",...

Transformations can also specify from which metas and labels they
depend, and add informations about how they are interpreted.

TODO:
  - complete and correct the documentation
  - when a transformation use Trans.on_meta, it should be possible to
    add an interpretation of the metas in the documentation.
  - recover a summary version of --list-* ?
  - be able to export in latex?

in particular, there is no more need to define intermediate
sorts or to close the set of protected types wrt subtyping

What was its purpose in the first place? Integers are protected
in Simplify anyway and then we can simply forget the difference
between the infinite sorts (as we do in encoding_tptp).

TPTP/simplify : explicit not anymore the default

Currently only in the driver z3_array.drv

- bring driver syntax closer to that of theories
- some simple API improvements

- everything is converted to the new shiny way of doing things.
  Well, everything except Gappa, which seems very unifinished anyway,
  and Encoding_instantiate, which is too complex and would like to 
  update it with François.

Also, I commented a little piece of exception reporting in manager/,
will see it with Claude.

THIS IS STILL A WORK IN PROGRESS!
Please inform me about any bugs, ugly APIs, and proposed corrections.

All the non-implemented things, mentioned in the previous commit
message are still in the TODO list and will be done soon.