[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)

[E-ACSL] use -e-acsl-check for all tests
[E-ACSL] prepare guarding division and module (commented code yet)

   o logical operators still don't work
   o pointer operators untested
- bug fixed with type of int64 constants

- improve efficiency of mpz_clear generation
- don't run cast.i anymore (waiting for fixing issue #744)
- refactoring generation of new variables with their related stmts

- reject \valid
- improve efficiency for vstmt_aux

- generated C headers in a separate file "share/e_acsl.h"
- fixed generation for Pnot
- some additional tests

- generating project is compilable
- first test case (for assert \true and \false)