Parentheses omitted when IF THEN ELSE optimization is applied

[chrispcampbell]

I found an issue with the IF THEN ELSE optimization that was implemented for #102. When the optimization is applied, the code gen failed to preserve the parentheses, which are sometimes critical.

Example that demonstrates the problem:

constant = 1 ~~|
a = IF THEN ELSE(constant, b + c, d - e) * 10 ~~|

In this case, SDE currently generates incorrect code:

_a = _b + _c * 10;

It should instead preserve the parentheses:

_a = (_b + _c) * 10;