Remove a lot of warnings (considered as errors by dune).

by
- remove duplication (add a profile_info function ine Lv6Verbose
- be more efficient (computing Sys.time only when necessary
- control the time-profiling printing via the -dbg flag "profile", and
  not the verbosity level

Ditto for Misc and Compile

As far as ldbg is concerned, it only traces the toplevel node, at
call event.

Note that I needed to rename quite a lot of modules to avoid name clashes
between lus2lic.a and ltop.

I've also merged the Verbose module with the one of Lutin so that
they can be shared (there were sharing 95% already).

sensible to flushing, which is painful.

Ident.t is now an abstract data type (instead of a string).
fullid is turned into an Ident.long, and is also made abstract.