Make both importers work the same way: first building an array
of the new offsets, then comparing the offsets to check if the
topology changed. Previously the USD importer incorrectly
compared curve offsets to USD point counts.
Also:
- Don't unnecessarily set the resolution to the incorrect default.
The default for the curves system is 12. But it's unnecessary to
fill the attribute to the default value anyway.
- Use some helper methods to iterate over all curves.
- Use float literal instead of integer.
Hans Goudey