Report error when writing to const array elements.
Merge pull request #451 from vasslitvinov/array-const-checking

Report error when writing to const array elements.

It is a small change to functionResolution.cpp. I introduced a new pragma flag that says "when the receiver is constant, the result is constant". Then followed the pattern of/relied on const checking that already was in place.

Several tests updated 'const' arrays. I replaced 'const' with 'var' on those arrays.

In one test I used an array literal for initialization of an array, which remained 'const'.

Reviewed by Tom.