Add GUI support for selecting routing protocols in use on virtual

Add GUI support for selecting routing protocols in use on virtual
routers.  The GUI now provides menus for enabling / disabling RIPv2,
RIPng, OSPFv2 and OSPFv3, as well as mechanisms for automatic
generation of appropriate quagga / xorp config files.  Routing
protocols can only be enabled or disabled on per-router basis, i.e.
no finer-grain control over individual routing protocol parameters
or options is provided.  If required, users can extend the
machine-generated quagga or xorp config file skeletons using the
"Custom config" menu option.

By default, all new quagga or xorp router instances will have both
RIPv2 and RIPng enabled, just as it was before this change.  The
defaults can be changed in menu Tools -> Routing protocol defaults,
which will be applied both to all selected routers (if any) at the
time of change, as well as to all the subsequentially created ones.

Thanks Ana!!!

Bug found by:
Submitted by:	Ana Mijocevic <ana.mijocevic at fer.hr>
Reviewed by:
Approved by:
Obtained from: