Allow unicode cdot to be considered operator alongside *

[superyuuki]

Sometimes you want to assign unicode cdot to dot product, etc but latexify will render it like a function. This PR should allow the unicode cdot to be rendered like the asterisk. It is also immune to kwargs cdot = false because sometimes you want to notate the dot in certain circumstance, etc

[gustaphe]

Nice idea! I think it would be better for maintainability to add :⋅ => "\\cdot" to arithmetic_operators in symbol_translations.jl, then the rest should follow automatically.
I should probably document this somewhere.

Could you write some tests? Especially try to catch the "is not affected by cdot=false" behavior, and that it's parenthesized correctly.

[superyuuki]

That's a good suggestion. I'll try to write some tests as well.