Initial set functionality support for associative arrays and domains
Simple tests for set features
Splitting tests into appropriate directories
op= set support for associative arrays
op= tests for associative arrays and domains
Simple subset test
Simplify 'proc -' for domains as sets
Merge branch 'master' of github.com:chapel-lang/chapel into sets
Making domainSetOps.chpl validate itself instead of matching some text output
Removing text output as assertions are sufficient for validation
Improving reliability of arraySetOps test
Replace <locale>.numCores with <locale>.maxTaskPar where appropriate.
Remove an extraneous space character.
Adding version of subset to produce compiler error when used with incompatible type
Enforcing 1:1 domain:array relationship for op= set operations on arrays
Adding comment blocks describing set operations
Parallelizing set operations when possible
Add real comments to yields in qthreads sync var lock and unlock

These were added to resolve deadlock that cropped up when we switched to the
nemesis scheduler. I never commented them properly because we weren't sure it
was the final solution or if the values were good. Things seem to be in good
shape some I'm adding extensive comments.
Stop performance testing if OPTIMIZED=1 build failed

* If the compiler OPTIMIZED=1 build fails, turn off compiler perf testing.
* If the runtime OPTIMIZED=1 build fails and it is a performance test run, it
  is a fatal error, so send the failure message and exit.
* Added the ability to exit on a fatal error back to mysystem after it was
  accidentally removed in a previous commit.

Tested by doing: nightly -debug -performance -notest
with and without things to warn about added to the compiler and runtime.
Wordsmithing based on gregs review