Remove and relocate most auxfunctions and update references

* make_dictionary deprecated by dict comprehension
* dict_append deprecated by setdefault
* dict_add deprecated setdefault
* list_split replaced by partition (clarity / standardization ([a](https://docs.python.org/3.4/library/itertools.html#itertools-recipes), [b](http://www.haskell.org/hoogle/?hoogle=partition), [c](http://www.cplusplus.com/reference/algorithm/partition/)))
* iterator_remove deprecated by filter
* fetch moved to its proper location in DBCtrl
* update moved to its proper location in SpikeDB