adding magic-latex-buffer package to latex layer

[benquebec]

the package allows some customization of font locking particularly useful with symbols

[StreakyCobra]

No luck again :-) When you created your magic branch, you did it from the aucreftex one and not from develop, so magic have herited all aucreftex commits. So if you look at this PR, you have both the changes of this one, plus the changes of #4153. At they are both latex related and concerning the same file, we will keep this commit and review both changes at the same time ☺️. I'll close the other PR then 😉

[benquebec]

still learning ;)

[yilihong]

any updates on this one?

[benquebec]

I ended up installing the package on my .spacemacs
Worked fine for my use.

[TheBB]

Thanks! Cherry-picked in develop. You can safely delete your branch.

I ended up just picking the magic-latex-buffer commit. Unfortunately this PR is too old for me to resolve any conflicts originating from a major overhaul of keybindings. Therefore please resubmit such changes if you like.

From experience such a package will be controversial so I made it optional and not default. I also turned off some of the more egregious effects by default (alignment and inline images).