Move iterator support functions out of ChapelArray and into a new module

Added a new internal module for iterator support functions and moved the
functions out of ChapelArray.  Updated tests that expected errors/warnings
from these functions to come from ChapelArray.  Updated a test that counts
dead modules to expect one more.
Merge pull request #861 from daviditen/iteratorSupportModule

Move iterator support functions out of ChapelArray and into a new module

Added a new internal module for iterator support functions and moved the
functions out of ChapelArray. Updated tests that expected errors/warnings
from these functions to come from ChapelArray. Updated a test that counts
dead modules to expect one more.

[reviewed by lydia-duncan]