Fixed 'findall()' so it only returns regular files -- no directories.

Fixed 'findall()' so it only returns regular files -- no directories.
Changed 'prune_file_list()' so it also prunes out RCS and CVS directories.
Added 'is_regex' parameter to 'select_pattern()', 'exclude_pattern()',
  and 'translate_pattern()', so that you don't have to be constrained
  by the simple shell-glob-like pattern language, and can escape into
  full-blown regexes when needed.  Currently this is only available
  in code -- it's not exposed in the manifest template mini-language.
Added 'prune' option (controlled by --prune and --no-prune) to determine
  whether we call 'prune_file_list()' or not -- it's true by default.
Fixed 'negative_opt' -- it was misnamed and not being seen by dist.py.
Added --no-defaults to the option table, so it's seen by FancyGetopt.