Fix pyparsing recursion issue

[Vlek]

When checking for recursion issues using pyparsing's built-in method, it flags as there being one.

What I found is that this happens whenever we have the dice notation supplied for both one and two operands being available. This likely means that there is a better way to do what we're doing, potentially moving away from the inFixNotation or adding an optional number for the left operand in the 1 operand statement and removing the other.

[Vlek]

Tests should be generated for this and other pyparsing issues as well!

https://github.com/pyparsing/pyparsing/wiki/Parser-Debugging-and-Diagnostics

[Vlek]

Also, we can remove the second unary minus, it's no longer needed with refactor.

[Vlek]

This may resolve our ((((((((((1 + 1)))))))))) max recursion depth issue. If it does not, we will have to create a separate issue to address it.

[Vlek]

This issue may also come with a parser speed hit which may impact our speed metrics in #41. This issue should be considered related until we know otherwise.