Reimplement the NSTL_INHERIT macro.
Reimplement the NSTL_INHERIT macro.

The goal is to make it faster and easier to understand. Also, a bug was fixed
because inherited fields would not be inherited when the same field was set
earlier during object construction.

The NSTL_INSTRUCITON_getf macro was also removed, because it was useless in
its current state.

ldionne/nstl,ldionne/nstl