[E-ACSL] compute a more precise type for quantified variable with a strict upper bound
[E-ACSL] do not modify the type of a quantified variable anymore

* fixes bug:
  - fixed bug in quantifications when the bound variable got C type
  - fixed bug with DEV_FLAGS in Makefile.in
* implements new E-ACSL features:
  - invariant as assertion
  - existential quantification \exists over integers
  - equivalence <==>
  - \at as a predicate
  - conditional _ ? _ : _ (for terms and predicates)
  - binary boolean operations over terms
  - mixed assumes and ensures in function contracts
* other new features:
  - better error messages when runtime checks fail 
    (replace e_acsl_fail by e_acsl_assert)
  - remove option -e-acsl-assert
  - add E-ACSL manuals in doc/manuals
  - add files doc/Changelog, INSTALL, README and VERSION
  - new option -e-acsl-version
  - check Frama-C version at configure
  - make src-distrib
  - header 2012

[e-acsl] universal quantifications done (including testing)

[e-acsl] universal quantifiers over integers. Not yet finished: work only in some cases
[e-acsl] logic variables (required by univ quantif)

[e-acsl] tests now independent of GMP version (but GMP still required)

[e-acsl] support of \at for stmt labels

[e-acsl] support of assumes without ensures in stmt contracts
[e-acsl] partial support of function contracts (the same subset than stmt contracts)
[e-acsl] additional test for nested code annotation
[e-acsl] code refactoring: visit.ml splitten into several compilation units

[e-acsl] Makefile's target 'install'
[e-acsl] test GMP linkage in non-regression suite ('make tests' now requires GMP >= 4.3.2)
[e-acsl] fixed bugs of GMP compatibility

- [Makefile] better generation of local_config.ml
- [Options] new options for customized code generation (unused yet)