The existing scribble/acmart language in this repo felt more like latex than Scribble. This package brings scribble/acmart more inline with the existing `scribble/acmart` package that was already on the package server. In particular, this commit:
* Remove maketitle from scribble/acmart
* Extends the title form to also have the fields in `scribble/base`'s title.
* Support author information. (Like scribble/sigplans authorinfo)
* Removed unneeded functions now redundant due to the author function. Namely, affiliation based ones.
* Factor out common functions to scribble/acmart and scribble/base into private module.
These functions might make sense to be public, but since they were already private in base
I thought it made sense to leave them that way. Additionally, it might make sense to have the
file be something other than private/tag, as private/tag currently requires tag, which is
different than the normal way where its tag that requires private/tag.
* Add short-title to scribble/latex-properties
* Adds an `command-optional` property which is like `command-extras`, but is a single
optional argument placed before the mandatory ones.
* Create email, affiliation, and institution structs so that authors can have multiple of each.
* Add/improve documentation and history (and bump version number).
