persistent_dict: add complex hashing, numpy scalar hashing (#184)

* persistent_dict: add complex hashing, numpy scalar hashing

* simplify

* fix

* better update_for_complex

* convert numpy scalars to 1D array

* use np.array instead

* tobytes() is not stable, try str+dtype

* fix number detection

* Revert "tobytes() is not stable, try str+dtype"

This reverts commit f1b766c791299b08bf4f7090b9b47b4dbfe2678a.

* Revert "fix number detection"

This reverts commit 078c75a4027146c8c4b27534e33b461e6cf908f1.

* convert large float types to python types

* Revert "Revert "fix number detection""

This reverts commit fc4350a8a526aebeea73f7ce15aa847bc76208da.