Change in vo format : digest aren't Marshalled anymore

 Since digests are strings (of size 16), we just dump them
 now in vo files (cf. Digest.output) instead of using Marshal
 on them : this is cleaner and saves a few bytes.

 Increased VOMAGIC to clearly identify this change in the format.
 Please rerun ./configure after this commit.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16722 85f007b7-540e-0410-9357-904b9bb8a0f7
More complete hashcons : lists (dirpath), arrays (constr)

Earlier, the elements of constr arrays were hash-consed, but not the
array itself. This helps a bit when the same (f a1 ... an) is manipulated
a lot : -20% in the size of opaque terms in Integral_domain.vo and Nsatz.vo

Similarly it's interesting to hash-cons sub-lists for dirpaths,
since in Coq.A.B and Coq.A.C we could share Coq.A.

With this patch, the hash-consing of constr seems quasi-optimal:
Pierre-Marie's marshal compactor is unable to shrink opaque tables by
more than 2%, and this difference seems to be due to untyped compaction
(for the compactor Rel 1 = Prop Pos).

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16723 85f007b7-540e-0410-9357-904b9bb8a0f7
micromega: remove empty file CheckerMaker

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16724 85f007b7-540e-0410-9357-904b9bb8a0f7
Less "Coq" strings everywhere

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16725 85f007b7-540e-0410-9357-904b9bb8a0f7
Misc changes around coqtop.ml :

 - Revised Coqtop.parse_args in a cleaner and lighter style
 - Improved error message in case of argument parse failure:
   * tell which option is expecting a related argument
   * in case of unknown options, warn about them all at once
   * do not hide the previous error messages by filling the
     screen with usage(). Instead, suggest the use of --help.
 - Specialized boolean config field Coq_config.arch_is_win32
 - Faster Envars.coqlib, which is back to (unit->string), and
   just access Flags.coqlib. Caveat: it must be initialized once
   via Envars.set_coqlib
 - Avoid keeping an opened channel to the "revision" file
 - Direct load of theories/init/prelude.vo, no detour via Loadpath

Beware : ./configure must be runned after this commit

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16726 85f007b7-540e-0410-9357-904b9bb8a0f7
Nicer code concerning dirpaths and modpath around Lib

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16727 85f007b7-540e-0410-9357-904b9bb8a0f7