Add support for graphing implicit equations

[quantum9Innovation]

Add support for graphing implicit functions, which can be done by using Newton's method or another root-finding algorithm to graph zero sets of functions in $x$ and $y$.

Ex:
$$f(x,y)=x^2+y^2-1=0$$

Graphs the unit circle

Concerns

Graphing areas as well as segments will present certain challenges, as Hulet currently lacks support for graphing areas from equations. Additionally, if a root-finding algorithm like Newton's method is employed, it will have to find all visible roots, not just the closest to a given input, which will mean running the algorithm more than once for each point, which can incur additional computational cost.