Help display is broken

[yannoff]

Regression introduced in #53

$ bin/multi --help
Fatal: Tags precedence was not respected (wrongly nested closing tag) (code: 1), exiting.

Quick fix

• Remove caret symbols wrapping the argument name in Definition::getSynopsys()
• Add a special processing for line-feed \n chars: a new line means a new token

Long-term fix
PosixFormatter should only take for granted a list of known tags, ie <name> should not be considered as a tag, since it is not in the tags/modifiers mapping.