Add balanced-parenthesis detection when parsing.

[jn1z]

This makes the dreaded "Formula contains one or more grammatical parse errors" clearer when left- and right- parens are not balanced.

Remove a couple of unused methods and variables, and extract redundant code. Use principle-of-least-permissions for some methods.

Add basic Linux batch files.

[jn1z]

Thanks for the detailed review! I'll see if there are ways to resolve the issues you mentioned.