newton api wrap to nodejs
example :
yield newton.simplify('x(x+1)') // x^2 + x
example:
yield newton.factorize('x^2-x') // x(x-1)
yield newton.derive('x^2+2x-1') // 2x -1
yield newton.findRoot('x^2+3x+2') // [-1, -2]
yield newton.integrate('x^2+x') // 1/3 x^3+1/2 x^2
// if a and b are given the integrate is defined
yield newton.integrate('x^2+x',0,1) // 1/3 + 1/2
yield newton.findTangent('x*x+ x*x*x-3x') // -3 x + -30