Further changes to permutedims and tests

With this commit, all tests pass. I changed the permutedims tests to
have permutations specified by vectors instead of tuples (which is also
how it is stated in the manual). I also had to make two seperate
versions of permutedims!: when B is a BitArray, P has to be a BitArray,
whereas for B a StridedArray, P should be an Array. I don’t think it is
possible to obtain this behavior in a single parametric definition.