Fix ArrayContains and ArrayIndex Nodes

[t3du]

Both nodes returned -1 for vector items or array items (the case when the input array is an array of more than one dimension), even though those items did indeed exist in the array. That's because the indexOf function of the array class does not handle the comparison properly.

With this fix now the comparison is handled and the correct value is returned for both nodes.

[MoritzBrueckner]

Same as #2781 (comment), I don't think you should use string representations for comparison of values (also regarding #2783). Depending on the amount of redundant code introduced by value comparisons, Armory might profit from a method compareDynamic() or equalsDynamic() that could then be used by various nodes.

[t3du]

Well, in the meantime is not working at all. While the efficient code arrives, this can comply the comparison.