Document hroller options recently added

Document hroller options recently added

hroller now also supports the options --skip-non-redundant and
--ignore-non-redundant, and this should be documented in the
man page as well.

While there, also use the same order in the options section
as in the synopsis, and in the synopsis group the algorithms
into
- those that modify the set of nodes to be scheduled, and
- those that modify the constraints to be taken into account.

Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>