ToricHigherDirectImages for JSAG

[sashahbc]

This is a draft PR for the review process of ToricHigherDirectImages for JSAG.

Since I had the chance to make some minor changes, I changed frobeniusDirectImage to frobeniusPushforward, but added it as a synonym (hopefully this means I don't need to revise the paper..?).

The original PR for the package is at #3720.
Other related PRs fixing minor bugs are: #3729, #3757, #3823, and #3884.

[d-torrance]

Yay -- pull request #4000!!!! 🎉 🥳

[antonleykin]

A cleaner way to declare a synonym would be to write

"frobeniusDirectImage" => "frobeniusPushforward"

(on line 38) and then get rid of anythin that mentions frobeniusDirectImage in the rest of code and documentation.

[antonleykin]

In general, the code look very clean! Two things to point out:

• use synonyms where appropriate: apart from "frobeniusDirectImage" => "frobeniusPushforward", disabbreviate/export and make a synonym "HDI" => "higherDirectImages".
• consider deleting some unnecessary "(" and ";" --- e.g.,

  M2/M2/Macaulay2/packages/ToricHigherDirectImages.m2

  Line 146 in 219355b

  frobeniusPushforward (ZZ, Complex) := Complex => (p, K) -> (

  and

  M2/M2/Macaulay2/packages/ToricHigherDirectImages.m2

  Line 59 in 219355b

  frobeniusPushforward = method();

• replace tabs with spaces (for consistent alignment) --- e.g.

  M2/M2/Macaulay2/packages/ToricHigherDirectImages.m2

  Lines 253 to 254 in 219355b

  	if count == #mons_0 then quotrays = append(quotrays, (Xrays)_i);
  	count

Documentation:

• use simple doc items like References, Contributors, etc. --- https://macaulay2.com/doc/Macaulay2/share/doc/Macaulay2/SimpleDoc/html/_package__Template.html --- in the main doc node
• consider merging similar doc nodes, where appropriate
• consider putting more links in SeeAlso sections

(Reviewed in consultation with @d-torrance and @mikestillman)