Add extension capability to table and dtype

[JimHofman]

Add the capability to extend Classes with table and dtype

[MJJoyce]

Working on a patch for dtype extensions support. Will have a PR up shortly for review

[cswoodruff]

It seems like extending CustomTypes requires python 3.10 or greater given the example code in the documentation. If so, this should be reflected in the install instructions.

class MyCustomTypes(dtype.CustomTypes):
    def get(self, typename: str) -> Optional[dtype.PrimitiveType]:
        match typename:
            case 'My24BitMSB':
                return My24BitMSB()

        return None

[MJJoyce]

Hey @cswoodruff, I'm guessing you're referencing the match in the example? Or something else and I'm just overlooking it? There's no "requirement" there beyond overwriting the interface.

[cswoodruff]

I was referring to the match in the example. It just caught me off guard because my virtualenv was running with python3.8 and I tried the example listed in the documentation and it failed.

[MJJoyce]

I was referring to the match in the example. It just caught me off guard because my virtualenv was running with python3.8 and I tried the example listed in the documentation and it failed.

Updated in 69ad7fe3abfd497e6ad989b10aa40f84137d093e