Vizzy: Render parentheses when low precedence operators nested inside higher precedence operators

In Vizzy since every operator is an independent node in a tree there is no ambiguity with regard to precedence of operations, however when looking at an expression that mixes * / and + - it can be difficult to see the nesting order without zooming in quite a bit (at least for old farts like myself with less than perfect eyesight). This could be alleviated by rendering parentheses around any operation that is nested inside of a different type of operation with the same or higher precedence. In other words a * b + c / d needs no parentheses assuming + is the root of the tree, and * and / are its children. Likewise a + b + c + d needs no parens because all the operators are the same. However (a + b) * (c - d) is easier to read with the parens so it isn't mistaken for a + (b * c) - d. I also think a / (b * c) and a + (b - c) should have parens because even though * and / are generally considered to have the same precedence the way these operation are grouped, when not interpreted purely from left to right, is significant. It should go with out saying that this only matters when a binary operator is nested inside another binary operator.