Katex-support in gogs

katexpatch.patch

diff --git a/templates/repo/view_file.tmpl b/templates/repo/view_file.tmpl
index 68e8444..38c790c 100644
--- a/templates/repo/view_file.tmpl
+++ b/templates/repo/view_file.tmpl
@@ -76,3 +76,26 @@ function submitDeleteForm() {
     }
 }
 </script>
+
+{{if .IsMarkdown}}
+<script src="//cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/katex.min.js"></script>
+<script src="//cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/contrib/auto-render.min.js"></script>
+<link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/katex.min.css">
+
+<script>
+function renderMath() {
+    renderMathInElement(
+        document.getElementById("file-content"),
+        {
+            delimiters: [
+                {left: "$$", right: "$$", display: true},
+                {left: "\\[", right: "\\]", display: true},
+                {left: "$", right: "$", display: false},
+                {left: "\\(", right: "\\)", display: false}
+            ]
+        }
+    );
+}
+renderMath();
+</script>
+{{end}}