Add a prototype of vector like functions on 1D arrays

This commit adds the following methods to the _array record.  They currently
apply to 1D unstridable rectangular arrays only.  The methods that resize
the array assert at runtime that there is a 1:1 correspondence between the
array and its domain.

front() // return the first element of the array
back() // return the last element of the array
empty() // is the array empty?
push_back() // put a new value at the back of the array
pop_back() // remove a value from the back of the array
push_front() // put a new value at the front of the array
pop_front() // remove a value from the front of the array
insert() // insert a new value at a specified position and shift other elements

The methods that change the array size call reallocate every time instead of
doing something smarter like a doubling/halving scheme.

Added a test that does some pushes and pops on an array.
Added a test that tries to push_back an array declared over a domain has
multiple arrays.
Add a simple array vector operations benchmark

This shows the performance of array vector operations.  There is plenty of
room for improvement because every operation reallocates currently.  It
should work as a perf test.
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
Merge remote-tracking branch 'origin/master' into vectorArray
Improving reliability of arraySetOps test
Move while stmt from block stmt 2 keywords to other.

Make while an other keyword (c-other-kwds) in emacs major mode instead of block
stmt with 2 keywords (c-block-stmt-2-kwds). Before this change, the indentation
for the block of while loops that did not surround the conditional in
parenthesis was broken.
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