Adding Extra Chars that are not supported by MathTeXEngine

[davibarreira]

Here is an example:

d = Drawing(400,200,:svg)
origin(100,50)
fontsize(20)
t = L"$x \in ℕ\cup${$-\infty,\, 0 \, , \infty$}"
text(t)

t = L"y \in 𝒞 \, , \, x \in ℬ \quad \frac{x}{y}"

text(t,Point(0,40))

fontsize(20)
t = L"f ⨟ h"
text(t,Point(0,70))
finish()
d

[davibarreira]

I messed up my git somehow, and I'm appearing with a bunch of commits ahead. I'll clean my fork and redo the PR.