Draft: Latexify integration

[pekpuglia]

Implement a simple Latexify interface through the conversion of polynomials to Expr's.

To Do:

• implement for monomials
• implement for polynomials
• maybe the conversion of Polynomial to Expr can be useful in some other parts of the code, e.g. code generation for polynomials. Should this be refactored elsewhere?
• implement some beautifying options in the latex recipe (maybe after the first merge.

Please review my Project.toml as well since this is my first package extension.

[pekpuglia]

After working on a MWE to get the types and structure right, I noticed there is a show method which already implements the "text/latex" MIME, with some more refined logic for printing variable subscripts, skipping unit coeffcients, etc. However, it lacks the flexibility of Latexify (which can seamlessly latexify Vector{Polynomial}, for instance, and format coefficients). I wonder if there is a way to re-use this logic to generate more clever Expr's for Latexify.