Comparison of `Timecode`s with different framerates is always `False`

[nickswalker]

timecode = Timecode(30, "00:00:00;00")
other_framerate = Timecode(60, "00:00:00;00")
print(other_framerate < timecode) # False
print(other_framerate > timecode) # False
print(other_framerate == timecode) # False

This may be surprising behavior, as users may expect the comparisons (if implemented and returning values) to obey trichotomy. I think it would be better to force users to define their own comparison in this case by raising an exception.