textproc/py-gladtex: [NEW PORT] LaTeX formula preprocessor for HTML files

Reworked following upstream switch from Perl to Python in version 1.6.

GladTeX is a preprocessor that enables the use of LaTeX maths within HTML
files. The maths, embedded in <EQ>...</EQ> tags, as if within \(..\) in
LaTeX (or $...$ in TeX), is fed through latex and replaced by images.

WWW: https://humenda.github.io/GladTeX/

PR: 280914
Approved by: yuri@ (Mentor)