Katex code from ink

Update postinstall.js

Author: aminya

lib/ui/katexify.js

@@ -0,0 +1,13 @@
+'use babel'
+
+// this file is lazy loaded by dynamic import simulation
+
+import { renderToString } from 'katex'
+
+export function texify (input, block) {
+    try {
+        return renderToString(input, {throwOnError: false, displayMode: block})
+    } catch (e) {
+        return input
+    }
+}

script/postinstall.js

@@ -1,8 +1,22 @@
 var fs = require('fs')
+var fsextra = require('fs-extra')
+var replace = require('replace-in-file')
 
 function copyKeymaps () {
   let suffix = process.platform === 'darwin' ? '.cmd' : '.ctrl'
   fs.copyFileSync(__dirname + '/../keymaps/julia-client.cson' + suffix, __dirname + '/../keymaps/julia-client.cson')
 }
 
+function installKaTeX () {
+  fsextra.copySync(__dirname + '/../node_modules/katex/dist/fonts', __dirname + '/../styles/fonts')
+  fsextra.copySync(__dirname + '/../node_modules/katex/dist/katex.css', __dirname + '/../styles/katex.css')
+
+  replace.sync({
+    files: __dirname + '/../styles/katex.css',
+    from:  /url\(fonts/g,
+    to:    'url(atom:\/\/ink\/styles\/fonts'
+  })
+}
+
 copyKeymaps()
+installKaTeX()