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, 1 insertions, 1 deletions

diff --git a/courseNotes/parallel.md b/courseNotes/parallel.md
index 7938119..551c1dc 100644
--- a/courseNotes/parallel.md
+++ b/courseNotes/parallel.md
@@ -1320,7 +1320,7 @@ MPI 点对点通信提供了阻塞和非阻塞两种通信机制，也支持多�
 <!-- 这幅图记得改，改成非阻塞通信的发送方与接收方的时序图 -->
 
 ```mermaid
-graph LR
+graph TD
 subgraph 阻塞通信
 A[发送]-->B[等待]
 B-->C[接收]