[WIP] LuaRuntime.table_from method

Implementation of #31.
Right, good call. Then checking for dicts is ok. It's easy enough to convert a non-dict mapping to a dict.

We could also make it configurable by accepting keyword arguments "mapping_types" and "sequence_types" that would default to ``dict`` and ``(tuple, list)`` respectively, and then do an isinstance() check with them (unless it's None). First check for the sequence types and only failing that, check for the mapping types. That way you can pass ``None`` for any of them to disable the conversion completely, or ``object`` to enable a specific conversion for all types, or any of the ABC classes, or whatever users want to come up with.