Projective Plane designs constructor
trac 15107 -- reviewer's comments
Rename the method from ProjectivePlaneDesign to DesarguesianProjectivePlaneDesign

Dima thinks that ProjectivePlaneDesign sucks because this code actually implements only one type of finite projective plane.
Rebase on 5.13.beta0
Trac #15107: Rebase on 6.1.beta3
trac #15107: back to the first name with a new argument
#6288: %lisp mode on the command line doesn't work. why?
trac #6288 addon and cleanup
Trac #15095: Symbolic hurwitz_zeta function
trac #15095 minor import changes
trac #15095 minor review patch
trac #15662 implement Ihara zeta function of graphs
fix my own wrong doc
trac #15662 better algo and better doc
trac #15662: Removing a 'if' in the algorithm
trac #15662 added more doc and changed name again
sanitize write permissions before creating tarballs
Some review changes to partition.py.
Fixed doc of young_subgroup() in partition.py.
trac #15662: Rebase on 6.1.beta5