Parens bug
Created by: mgmoens
Reproduction: try to use calc ((15+45)) in ion on my branch with the crate added in.
**Expected output **: 60
Actual output: ion: syntax error: '(' at position 6 is out of place
Misc: I'm probably the root for this bug :p I think I introduced a couple off by one out of bounds bugs.
If the above does not fit the nature of the issue feel free to modify it.