forked from: Graph 1.65

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@author Thi
Graph v. 1.65 / 2.0

some expresison samples:
0 + 1 - 2 * 3 / 4 ^ -5 +6143 = 0
-1 ^ round (x) - sin (x) + asin(x²) + (.08x² + .1x - 1)

pi = PI = 3.1415
e = E = 2.7182
round (x), floor (x), ceil (x)
log (x), exp (x)
sen (x) = seno (x) = sin (x)
cosseno (x) = cos (x)
tangente (x) = tangent (x) = tgt (x) = tg (x) = tan (x)
absoluto (x) = modulo (x) = abs (x)
aleatorio = random, 0 <= random > 1
raiz (x) = sqrt (x) = x ^ (1/2)
acos (x), asin (x), atan (x)

syntax observations:
a + b, a - b, a * b, a / b, a ^ b
a + b * c = a + (b * c)
a * b ^ c = a * (b ^ c)
a + b ^ c = a + (b ^ c)
a² = a ^ 2
a³ = a ^ 3
1x = (1)x = 1(x) = (1)(x) = x(1) = (x)1 = 1 * x

The calculator works using 3 main functions:
- Translate the string to an array, so it can be read
- Arranje it using Reverse Polish Notation (RPN)
- Return the value
We do this for 465 x points for each function for each graph!

TODO:
The scene 1 features (add new 'function', 'var', 'graph' etc)
but u can transit to scene 1 by