Add support for Solver Equations

Supports solving equations like:

• Simul Equation
  • 2 Unknowns
  • 3 Unknowns
  • 4 Unknowns
  • n Unknowns
• Polynomial
  • $ax^2 + bx + c$
  • $ax^3 + bx^2 + cx + d$
  • $ax^4 + bx^3 + cx^2 + dx + e$
  • $a_n x^n + a_{n-1}x + a_{n-2}x^{n-2} + \dots + a_1x^1 + a_0$
• Equation (Find values of variable)

Maybe this feature is not suitable for your library but it would be nice if it was added. I found a similar library for this feature but it seems to be no longer maintained. https://github.com/Samshal/Equation-Solver