Module permgroup_named

"Named" Permutation groups (such as the symmetric group, S_n)
           
You can construct the following permutation groups:

-- SymmetricGroup, $S_n$ of order $n!$ (n can also be a list $X$ of distinct 
                   positive integers, in which case it returns $S_X$)
      
-- AlternatingGroup, $A_n$ or order $n!/2$ (n can also be a list $X$ 
                   of distinct positive integers, in which case it returns 
                   $A_X$)
       
-- DihedralGroup, $D_n$ of order $2n$
       
-- CyclicPermutationGroup, $C_n$ of order $n$
       
-- TransitiveGroup, $i^{th}$ transitive group of degree $n$ 
                      from the GAP tables of transitive groups (requires
                      the "optional" package database_gap)

-- MathieuGroup(degree), Mathieu group of degree 9, 10, 11, 12, 21, 22, 23, or 24.

-- KleinFourGroup, subgroup of $S_4$ of order $4$ which is not $C_2 \times C_2$

-- PGL(n,q), projective general linear group of $n\times n$ matrices over 
             the finite field GF(q)

-- PSL(n,q), projective special linear group of $n\times n$ matrices over 
             the finite field GF(q)

-- PSp(2n,q), projective symplectic linear group of $2n\times 2n$ matrices 
              over the finite field GF(q)

-- PSU(n,q), projective special unitary group of $n\times n$ matrices having
             coefficients in the finite field $GF(q^2)$ that respect a 
             fixed nondegenerate sesquilinear form, of determinant 1.

-- PGU(n,q), projective general unitary group of $n\times n$ matrices having
             coefficients in the finite field $GF(q^2)$ that respect a 
             fixed nondegenerate sesquilinear form, modulo the centre.

-- SuzukiGroup(q), Suzuki group over GF(q), $^2 B_2(2^{2k+1}) = Sz(2^{2k+1})$.


AUTHOR:
    - David Joyner (2007-06): split from permgp.py (suggested by Nick Alexander)

REFERENCES:
    Cameron, P., Permutation Groups. New York: Cambridge University Press, 1999.
    Wielandt, H., Finite Permutation Groups. New York: Academic Press, 1964.
    Dixon, J. and Mortimer, B., Permutation Groups, Springer-Verlag, Berlin/New York, 1996. 

NOTE:
    Though Suzuki groups are okay, Ree groups should *not* be wrapped as 
    permutation groups - the onstruction is too slow - unless (for 
    small values or the parameter) they are made using explicit generators.