devfsctl - Cleanup and several bugfixes

devfsctl - Cleanup and several bugfixes

* split lines longer than 80 columns

* Moved TAILQ_INSERT* into get_rule to avoid a problem which
  caused groups to also be inserted and kept in the rule
  list

* Fix several bugs related to config file parsing, including:
  - a bug in the argument checker, which caused a SEGFAULT
  - a bug that would cause lines beginning with whitespaces
    to duplicate their first real token
  - an incorrect check for an empty line, which caused a
    warning about an incorrect verb instead of ignoring
    the line