Invalid generated code when model variable name includes parentheses

[chrispcampbell]

We have a model that has a variable name that includes parentheses, and we can't easily change it for [reasons]. This case is not currently handled correctly in SDE, so it results in incorrect generated code.

There are actually two problems:

1. During preprocessing when generating the key used for flattening, we split on (, but this code doesn't account for the case where the ( appears inside a quoted variable name. In the case of the sde flatten command, this means if you have two variables (Var (1) and Var (2), only the first one will be preserved in the preprocessed model.
2. During parsing, the canonicalId function does not transform paren characters to underscore like we do for other punctuation, so the generated C/JS code will include for example _var_(1) which is not a valid identifier.