Remove old help formatting code

Make parse_common_args() format its help using the new
CommandLineHelpWriter class.  To support this:
 - Add conversion functions that map t_filenm and t_pargs options to
   corresponding Option classes.
 - Add support for arbitrary file types from the filenm.h enum to
   FileNameOption.
 - Add support for writing a list of known issues from
   CommandLineHelpWriter.
 - Some minor extensions to the Option classes to make it easy to do
   the conversion.
 - Fix gmx_hbond to not specify the same option twice.
 - Remove wman.* as unused after the change.

Related to #969.

Change-Id: I25143ddfa4226abd5ae5b95172f69c8fc615b720
Make 'gmx -h' invariant wrt. provided options

The help output no longer depends on what the user provided on the
command line.  To do this, initialize a separate copy of the options
holder for writing the help.  This decouples the module manager and the
actual help output a bit more.  Make the option holder implementation
shared through cmdlinemodulemanager-impl.h.

Change-Id: I82ea1e969c7d02eadcb2a9f519af30561cb19991