Lost bits in value index (severe bug for some use cases) -- with FIX

[brandyn]

https://github.com/OpenZWave/python-openzwave/blob/8be4c070294348f3fc268bc1d7ad2c535f352f5a/src-lib/libopenzwave/values.pxd#LL51C1-L51C27

The GetIndex declaration should read uint16_t, not uint8_t (also need to add uint16_t to cimport line at top).

As-is, bits are dropped from the index, causing apparently-redundant values in any system that (reasonably) identifies values by cc/inst/index tuples.