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.
Start a travis config file.
Fix before_script.
Install csh.
Just use gcc for now.
Install bc on travis
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
Provide uniform isXxx functions in the standard modules.
Simplify 'proc -' for domains as sets
Merge branch 'master' of github.com:chapel-lang/chapel into sets
Bug fix/workaround for sync/single args; minor reformatting in ChapelSyncvar.chpl
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