to_latex confusing name

I would expect a function called `to_latex` to consume something (say unicode) and produce latex. But here it is the other way round:

```
latexstring = "\\alpha^2 \\cdot \\alpha^{2+3} \\equiv \\alpha^7"
to_latex(latexstring) == "α² ⋅ α²⁺³ ≡ α⁷"
```

Maybe `to_unicode` or `latex2unicode` would be a better name?
