Support for anonymous functions

[xwjqv]

Example

@latexify  x-> x^p

becomes

L"$x \mapsto x^{2}$"

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.02 :tada:

Comparison is base (8e74eed) 72.38% compared to head (0bb0d9a) 72.41%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #255 +/- ## ========================================== + Coverage 72.38% 72.41% +0.02% ========================================== Files 23 23 Lines 945 946 +1 ========================================== + Hits 684 685 +1 Misses 261 261 ``` | [Impacted Files](https://codecov.io/gh/korsbo/Latexify.jl/pull/255?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Niklas+Korsbo) | Coverage Δ | | |---|---|---| | [src/latexoperation.jl](https://codecov.io/gh/korsbo/Latexify.jl/pull/255?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Niklas+Korsbo#diff-c3JjL2xhdGV4b3BlcmF0aW9uLmps) | `85.21% <100.00%> (+0.10%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Niklas+Korsbo). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Niklas+Korsbo)

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[xwjqv]

Is there a problem merging this? The windows check failure seems unrelated.

[korsbo]

Hi, this looks fine to me. I've just been a bit detached from this package for a while due to life.

Thanks :)