highlight don't use auto-detect but given languagenew_highlightjs

In this commit, lot's of things is changed. Hope they all runs
currectly.

Now highlight.js is supporting more and more proguam languages,  but
the auto detection always go wrong, even for common languages like c,
bash, python, makefile.

Use Given Language
------------------

As you know, I always write markdown and convert to html by pandoc. In
the old, "```cpp" in markdown will be deleted first to keep the embeded
code clean and not highlighted, then I can use highlight.js. But this
causes that html document doesn't know the language.

This time, md2html.sh is changed: pandoc use "--no-highlight"
argument to keep code clean, and it will output like this:

```html
<pre class="cpp"><code>...</code></pre>
```

Although there may be other tags between `<code></code>`, it's clear
that `<pre class="xxx"><code>` is nested tightly, except some space
characters or \n.

Then, sed deal with the whole doc(not line by line), replace `<pre
class="xxx"><code>` with `<pre><code class="language-xxx">`. That's it!

Math Formula
------------

Math formular is also a problem during convertion by pandoc. In the old
it's dealed menually. Now pandoc use "--mathjax=none", then formula is
no longer showed by pandoc, but only `<span class="math xxx">\( formula \)</span>`.
And the math tool I used will deal with it.

Mermaid picture
----------------

pandoc doesn't support convert mermaid in markdown to html picture.
Let's have a warning!

1 files changed, 0 insertions, 11 deletions

diff --git a/code/zeal.md b/code/zeal.md
index eeccf7c..db552af 100644
--- a/code/zeal.md
+++ b/code/zeal.md
@@ -295,14 +295,3 @@ http://tokyo.kapeli.com/feeds/ZeptoJS.tgz
 下载完成后，对压缩包进行解压，并将解压所得文件夹整体放入上文规定的 Zeal 文档存储路径之下。
 
 重启 Zeal，即可在左侧看到信息，可以在左上角搜索了。
-
-# test
-
-```mermaid
-graph LR
-A[1]-->B[2]
-```
-
-$$
-\int_0^\frac \pi 2 \sin x =1
-$$