v0.3.5: Increase performance for repeated evaluations

Increase performance for repeated evaluations by keeping two stacks in the Calculator struct, rather than initializing and discarding for every evaluation.

v0.3.4: Breaking! Replace infixEquation.evaluate() with faster one-step implementation, shuffle around file and dependency structure

v0.3.4: Breaking! Replace infixEquation.evaluate() with faster one-step implementation, shuffle around file and dependency structure

v0.3.3: Update for zig build changes

This doesn't change anything with the calculator for the user, but upstream projects can now include this as a module properly on zig nightly.

v0.3.2: Support for infinity, -infinity, and NaN

Add support for infinity, -infinity, and NaN.

v0.3.1: Breaking Changes!

Commit notes:

Rename Equation to Calculator and make root of file to improve mental model of what the struct actually is.
Split Infix and PostfixEquation into separate files.
Make Calculator initializer take in function pointers to registrar functions instead.
Add errorDescription function.
Rename PostfixEquation.fromInfixEquation to init
Make Operator and methods public

v0.3.0: Functions and exponential notation

Version 0.3.0! Now supporting customization functions, constant values, and exponential notation!