- add a 
strict argument to transform_mathjax() (“ignore”
by default) to turn off ennoying warnings when using accented characters
in equations. 
- add a 
display argument to transform_mathjax() to allow
generating display or inline equations. It is set to FALSE by default
(inline equation). This changes the behaviour that was previously to
generate display equations only. 
- delete unused mathjax-npm related tools.
 
- drop the node.js dependency in favor of package katex.
 
- use tools::R_user_dir instead of rappdirs::user_data_dir as it’s a
condition to keep the package on CRAN (“This is using
^~/.local/share/equatags , prohibited by the CRAN policy. Please replace
the use of rappdirs by the allowed procedure documented there.”)