MaximalSubgroupClassReps uses AtlasRep if available

[hulpke]

MaximalSubgroupClassReps method for simple groups that uses AtlasRep, if thee package is available and can handle the group.

[fingolfin]

Thank you! Looks good to me but it wouldn't hurt if @ThomasBreuer had another look, perhaps?

[ThomasBreuer]

The idea is:
If AtlasRep provides information about the group in question then does it have SLPs for computing representatives for all classes of maximal subgroups?
In order to decide this, one can do the following.

info:= AtlasRepInfoRecord( name );
IsBound( info.nrMaxes ) and info.slpMaxes[1] = [ 1 .. info.nrMaxes ] and ForAll( info.slpMaxes[2], l -> 1 in l );

If the result is true then one can proceed as in the proposed code: Compute standard generators and use the SLPs directly if there is a find script, and compute an isomorphisms of groups and use AtlasSubgroup otherwise.

[fingolfin]

@ThomasBreuer does this seem OK to you now?

[ThomasBreuer]

Thanks.
The code looks correct now, just two lines could be simplified.

[fingolfin]

Thank you! I applied @ThomasBreuer tweaks (after double checking), this will auto-merge once the test suite passed