add shortname to IsomorphismTypeInfoFiniteSimpleGroup value

The record returned by `IsomorphismTypeInfoFiniteSimpleGroup`
contains a `name` component that is not suitable for
programmatic access.

The new component `shortname` fits to the names that are used in
`CTblLib` and `AtlasRep`.
It will simplify some of my example sessions.
In particular I will be able to get rid of some calls to
`StructureDescription`; I think it is not appropriate to advertise
that function by applying it to simple groups.

    TB

doc/tut/group.xml

@@ -202,7 +202,8 @@ gap> IsSimple( f ); IsomorphismTypeInfoFiniteSimpleGroup( f );
 true
 rec( 
   name := "A(1,7) = L(2,7) ~ B(1,7) = O(3,7) ~ C(1,7) = S(2,7) ~ 2A(1,\
-7) = U(2,7) ~ A(2,2) = L(3,2)", parameter := [ 2, 7 ], series := "L" )
+7) = U(2,7) ~ A(2,2) = L(3,2)", parameter := [ 2, 7 ], series := "L", 
+  shortname := "L3(2)" )
 gap> SetName( f, "L_3(2)" );
 ]]></Example>
 <P/>

lib/ctbl.gd

@@ -1163,18 +1163,22 @@ DeclareAttributeSuppCT( "OrdinaryCharacterTable", IsGroup, [] );
 ##  gap> List( tables, Size );
 ##  [ 3, 24, 60 ]
 ##  gap> IsomorphismTypeInfoFiniteSimpleGroup( CharacterTable( "C5" ) );
-##  rec( name := "Z(5)", parameter := 5, series := "Z" )
+##  rec( name := "Z(5)", parameter := 5, series := "Z", shortname := "C5" 
+##   )
 ##  gap> IsomorphismTypeInfoFiniteSimpleGroup( CharacterTable( "S3" ) );
 ##  fail
 ##  gap> IsomorphismTypeInfoFiniteSimpleGroup( CharacterTable( "S6(3)" ) );
-##  rec( name := "C(3,3) = S(6,3)", parameter := [ 3, 3 ], series := "C" )
+##  rec( name := "C(3,3) = S(6,3)", parameter := [ 3, 3 ], series := "C", 
+##    shortname := "S6(3)" )
 ##  gap> IsomorphismTypeInfoFiniteSimpleGroup( CharacterTable( "O7(3)" ) );
-##  rec( name := "B(3,3) = O(7,3)", parameter := [ 3, 3 ], series := "B" )
+##  rec( name := "B(3,3) = O(7,3)", parameter := [ 3, 3 ], series := "B", 
+##    shortname := "O7(3)" )
 ##  gap> IsomorphismTypeInfoFiniteSimpleGroup( CharacterTable( "A8" ) );
 ##  rec( name := "A(8) ~ A(3,2) = L(4,2) ~ D(3,2) = O+(6,2)", 
-##    parameter := 8, series := "A" )
+##    parameter := 8, series := "A", shortname := "A8" )
 ##  gap> IsomorphismTypeInfoFiniteSimpleGroup( CharacterTable( "L3(4)" ) );
-##  rec( name := "A(2,4) = L(3,4)", parameter := [ 3, 4 ], series := "L" )
+##  rec( name := "A(2,4) = L(3,4)", parameter := [ 3, 4 ], series := "L", 
+##    shortname := "L3(4)" )
 ##  ]]></Example>
 ##  </Description>
 ##  </ManSection>

lib/ctbl.gi

@@ -1456,23 +1456,29 @@ InstallMethod( IsomorphismTypeInfoFiniteSimpleGroup,
                       parameter:= [ n, q ],
                       name:= Concatenation( "B(", String(n), ",", String(q),
                                             ") ", "= O(", String(2*n+1), ",",
-                                            String(q), ")" ) );
+                                            String(q), ")" ),
+                      shortname:= Concatenation( "O", String( 2*n+1 ), "(",
+                                                 String(q), ")" ) );
         else
           type:= rec( series:= "C",
                       parameter:= [ n, q ],
                       name:= Concatenation( "C(", String(n), ",", String(q),
                                             ") ", "= S(", String(2*n), ",",
-                                            String(q), ")" ) );
+                                            String(q), ")" ),
+                      shortname:= Concatenation( "S", String( 2*n ), "(",
+                                                 String( q ), ")" ) );
         fi;
       elif 15 in SizesCentralizers( tbl ) then
         type:= rec( series:= "A",
                     parameter:= 8,
                     name:= Concatenation( "A(8) ", "~ A(3,2) = L(4,2) ",
-                                          "~ D(3,2) = O+(6,2)" ) );
+                                          "~ D(3,2) = O+(6,2)" ),
+                    shortname:= "A8" );
       else
         type:= rec( series:= "L",
                     parameter:= [ 3, 4 ],
-                    name:= "A(2,4) = L(3,4)" );
+                    name:= "A(2,4) = L(3,4)",
+                    shortname:= "L3(4)" );
       fi;
     fi;
     return type;

lib/grp.gd

@@ -3816,11 +3816,18 @@ DeclareOperation( "IntermediateSubgroups", [IsGroup, IsGroup] );
 ##  <Description>
 ##  For a finite simple group <A>G</A>,
 ##  <Ref Func="IsomorphismTypeInfoFiniteSimpleGroup" Label="for a group"/>
-##  returns a record with the components <C>series</C>, <C>name</C>
-##  and possibly <C>parameter</C>,
+##  returns a record with the components <C>name</C>, <C>shortname</C>,
+##  <C>series</C>, and possibly <C>parameter</C>,
 ##  describing the isomorphism type of <A>G</A>.
-##  The component <C>name</C> is a string that gives name(s) for <A>G</A>,
-##  and <C>series</C> is a string that describes the following series.
+##  <P/>
+##  The values of the components <C>name</C>, <C>shortname</C>,
+##  and <C>series</C> are strings,
+##  <C>name</C> gives name(s) for <A>G</A>,
+##  <C>shortname</C> gives one name for <A>G</A> that is compatible with the
+##  naming scheme used in the &GAP; packages <Package>CTblLib</Package> and
+##  <Package>AtlasRep</Package>
+##  (and in the &ATLAS; of Finite Groups&nbsp;<Cite Key="CCN85"/>),
+##  and <C>series</C> describes the following series.
 ##  <P/>
 ##  (If different characterizations of <A>G</A> are possible
 ##  only one is given by <C>series</C> and <C>parameter</C>,
@@ -3927,7 +3934,8 @@ DeclareOperation( "IntermediateSubgroups", [IsGroup, IsGroup] );
 ##  >                             Group((4,5)(6,7),(1,2,4)(3,5,6)));
 ##  rec( 
 ##    name := "A(1,7) = L(2,7) ~ B(1,7) = O(3,7) ~ C(1,7) = S(2,7) ~ 2A(1,\
-##  7) = U(2,7) ~ A(2,2) = L(3,2)", parameter := [ 2, 7 ], series := "L" )
+##  7) = U(2,7) ~ A(2,2) = L(3,2)", parameter := [ 2, 7 ], series := "L", 
+##    shortname := "L3(2)" )
 ##  ]]></Example>
 ##  <P/>
 ##  For a positive integer <A>n</A>,
@@ -3940,8 +3948,9 @@ DeclareOperation( "IntermediateSubgroups", [IsGroup, IsGroup] );
 ##  two possible isomorphism types of simple groups of this order.
 ##  <P/>
 ##  <Example><![CDATA[
-##  gap> IsomorphismTypeInfoFiniteSimpleGroup( 5 );    
-##  rec( name := "Z(5)", parameter := 5, series := "Z" )
+##  gap> IsomorphismTypeInfoFiniteSimpleGroup( 5 );
+##  rec( name := "Z(5)", parameter := 5, series := "Z", shortname := "C5" 
+##   )
 ##  gap> IsomorphismTypeInfoFiniteSimpleGroup( 6 );
 ##  fail
 ##  gap> IsomorphismTypeInfoFiniteSimpleGroup(Size(SymplecticGroup(6,3))/2);