Add AviSynth support to prism.js

[Zinfidel]

AviSynth support has been officially added to PrismJS (PrismJS/prism#3071).

I updated this prism.js file by copying the link in the comment at the top, adding the AviSynth option, and downloading. I think it looks as different as it does because the site seems to be alphabetically sorting the url now, and other changes have probably taken place in the included languages since the file was originally added.

[Zinfidel]

Resolves #384

[vadosnaprimer]

So which languages do we highlight so far?

[Zinfidel]

The DL link at the top of the file will take you to the DL page with all options checked:
https://prismjs.com/download.html?#themes=prism&languages=markup+css+clike+javascript+abap+actionscript+ada+apacheconf+apl+applescript+arduino+asciidoc+aspnet+asm6502+autohotkey+autoit+avisynth+bash+basic+batch+bison+brainfuck+bro+c+csharp+cpp+coffeescript+crystal+css-extras+d+dart+diff+django+docker+eiffel+elixir+erlang+fsharp+flow+fortran+gherkin+git+glsl+go+graphql+groovy+haml+handlebars+haskell+haxe+http+ichigojam+icon+inform7+ini+io+j+java+jolie+json+julia+keyman+kotlin+latex+less+livescript+lolcode+lua+makefile+markdown+markup-templating+matlab+mel+mizar+monkey+n4js+nasm+nginx+nim+nix+nsis+objectivec+ocaml+opencl+oz+parigp+parser+pascal+perl+php+php-extras+powershell+processing+prolog+properties+protobuf+pug+puppet+pure+python+q+qore+r+jsx+reason+renpy+rest+rip+roboconf+ruby+rust+sas+sass+scss+scala+scheme+smalltalk+smarty+sql+stylus+swift+tcl+textile+twig+typescript+vbnet+verilog+vhdl+vim+wiki+xeora+xojo+yaml

[vadosnaprimer]

Hey looks like we're gonna need Razor C#.

Also maybe a few plugins: Line Numbers, Show Language, Copy to Clipboard Button, and Download Button.

[nattthebear]

Also maybe a few plugins: Line Numbers, Show Language, Copy to Clipboard Button, and Download Button.

Line numbers sounds OK, but we already have our own mechanism for download button that matches the old site behavior, as well as showing what language it is