Make nd_uint8_t and nd_int8_t arrays, to catch direct references.

Make nd_uint8_t and nd_int8_t arrays, to catch direct references.

This catches direct references, so we can change them to use EXTRACT_U_1
or EXTRACT_S_1.

Also, change some structures to use the nd_ types that weren't already
using them.

Then make the appropriate EXTRACT_{U,S}_1() changes.