Improve order of code generation calls

This allows for subject coders to be constructed with results
from the Generate method on mixin coders.
Separate subject method iteration

Introduce new class to handle iteration of methods outside of
ProxyClassCoder.  This is planned for use with upcoming changes
for computing per-method values and use of method index.
Add missing prime call in benchmarks
Compute index for method; method exists from index

Rather than compute method exists directly, the library now computes
the index of the method then determines whether the method exists
based on the index.  This does slow down the general case, but 1)
there are more improvements to be made; 2) it now allows for an
even faster scenario where the method index is cached for repeated
use; 3) it will allow safe proxy to use method exists more
quickly and easily.