Roadmap for Permuta

Updated (22.11.2016)

• Murray and Raggi (maybe with Bjarki's input) will lay down the law on code style.
• Define method ordering.
• Discuss Permutations class, should this be a class method in Permutation? (22.11.2016)
• Moving Permutations class into avoidance class as avoidance class of empty set. (22.11.2016)
• Rename avoidance class to Permutations. (22.11.2016)
• Struct needs fixing. (22.11.2016)