Refactor, fix, and simplify argument checking

__process_positional_parameters():
  Separate the catchall (shortcut) operations like '-l, --all' and
  '-L, --reallyall' into a loop before processing individual arguments.
  This allows the duplications and conflicts to be accurately
  determined, no matter of the order of invocation.

  Added some conflicting logic to 'aucdtect' and 'replaygain'
  operations.

__check_conflicting_operations():
  Removed lots of antiquated code, removing the last vestiges of unused
  variables.

  Only check for conflicting operations if '-l, --all' or
  '-L, --reallyall' was called, removing the duplication of operations
  that may be called.  For example, if '-L' was called, this script will
  allow '-m' to be specified, removing complicated duplication checking
  since '-m' doesn't conflict with '-L'.