Add comments describing the new array vector style methods
Add comments describing the new array vector style methods

Add comments ahead of each of the new array vector style methods. Also, added
_array.idxType to match _array.eltType and switched from this._value.idxType
to this.idxType and from this._value.eltType to this.eltType.

CoryMcCartan/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,chizarlicious/chapel,CoryMcCartan/chapel,chizarlicious/chapel,chizarlicious/chapel,chizarlicious/chapel,CoryMcCartan/chapel,hildeth/chapel,chizarlicious/chapel,hildeth/chapel,hildeth/chapel,hildeth/chapel,chizarlicious/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,chizarlicious/chapel,hildeth/chapel,hildeth/chapel,hildeth/chapel