Preprocessor is now a library installed by opam.
Replaced ligolang@gmail.com by contact@ligolang.org in opam files.
Reformatted some opam files.
Removed #line directive from preprocessor.
Added to the interface of ParserUnit.
Script messages.sh now checks the identity of .msg and .msg.old
to avoid undue warning about possibly different LR items.
* The parameter for logging the lexer is now mandatory.
* The ParserAPI now thread the logging of the lexer.
* LexerMain.ml now call the logging of the lexers (CameLIGO, ReasonLIGO).
* Fixed bug in lexer when a line comment ends with EOF.
