gsort() tests split, factorized, extended to u-int64

gsort() tests split, factorized, extended to u-int64

  * gsort.tst split:
    - complex: gsort.tst => gsort_complex.tst
    - sparse:  gsort.tst => gsort_sparse.tst (including complex sparse)
    Indeed, forthcoming devs about sorting complex numbers and sparse
    will increase a lot the dedicated tests, while gsort.tst is already
    huge.
    Not a single test removed or changed, just transfered.

  * In gsort.tst:
    - Tests of u-int8-16-32 were 6 times the same code
      => heavily factorized in a inttype=[1 2 4 8 11 12 14 18] loop.
      The content of the loop is unchanged (except to iconvert() things)
    - int64 and uint64 integers were not tested
      => inttype = [8 18] added to the testing loop.
    - hypermatrices: twice the code => o = ["i" "d"] loop

Change-Id: I83dd1349d7f4c08190c2622236f213d697f79753