Add operator intentions

Add intentions for replacing attribute calls that correspond to
overloadable operators with their respective operators.

This commit includes call replacements for:
 * Binary Infix Operators: plus, minus, times, rangeTo, mod, div
 * Unary Prefix Operators: plus, minus, not
 * Array Index Operator: get
 * In Operator: contains

This does not include set, put, *Assign, etc...