Fails in Python 3.10

[Gerenuk]

pyRMT.py fails in Python 3.10 on from collections import MutableSequence, Sequence since apparently in Python 3.10 it should be from collections.abc import ...

[dvolgyes]

The collections.abc has these since python 3.5:
https://docs.python.org/3.5/library/collections.abc.html#collections.abc.MutableSequence

So the trivial fix would be just update the imports from "collections" to "collections.abc".
There is even a pull request for the trivial fix, so please, pull it. #2

There are other projects depending on this repository, like WeightWatcher, which cannot be used with python 3.10
until this is fixed (or WW moves to a fork.)