Several bug fixes and improvements (#945)

* Update Dockerfile for code debugging.

* Format Python code using Black.

* Improve dark theme by defining html classes for the figures, animations and cover images.

* Fix several glossary translation.

* Update a code comment.

* Fix climbing_stairs_backtrack: the pruning should not require the sorted choices list.

* Update the code of array and list traversal.

* Fix a rendering issue of README.md

* Update code of list traversal.

* Fix array_definition.png

* Update README.md

* Fix max_capacity_moving_short_board.png

* Fix array.dart

* Fix array.dart

* Fix array.dart

* Fix array.dart

README.md

@@ -1,7 +1,6 @@
 <p align="center">
   <a href="https://www.hello-algo.com/">
-    <img src="https://www.hello-algo.com/index.assets/hello_algo_header.png" width="450">
-  </a>
+    <img src="https://www.hello-algo.com/index.assets/hello_algo_header.png" width="450"></a>
 </p>
 
 <p align="center">
@@ -12,11 +11,9 @@
 
 <p align="center">
   <a href="https://www.hello-algo.com/">
-    <img src="https://www.hello-algo.com/index.assets/btn_read_online_dark.png" width="155">
-  </a>
+    <img src="https://www.hello-algo.com/index.assets/btn_read_online_dark.png" width="155"></a>
   <a href="https://github.com/krahets/hello-algo/releases">
-    <img src="https://www.hello-algo.com/index.assets/btn_download_pdf_dark.png" width="155">
-  </a>
+    <img src="https://www.hello-algo.com/index.assets/btn_download_pdf_dark.png" width="155"></a>
 </p>
 
 <p align="center">
@@ -66,7 +63,7 @@
 
 - [内容修正](https://www.hello-algo.com/chapter_appendix/contribution/)：请您协助修正或在评论区指出语法错误、内容缺失、文字歧义、无效链接或代码 bug 等问题。
 - [代码转译](https://github.com/krahets/hello-algo/issues/15)：期待您贡献各种语言代码，已支持 Python、Java、C++、Go、JavaScript 等 12 门编程语言。
-- [整书翻译](https://github.com/krahets/hello-algo/tree/en)：诚邀您加入我们的中译英小组，成员主要来自计算机相关专业、英语专业和英文母语者。
+- [Chinese-to-English](https://github.com/krahets/hello-algo/tree/en)：诚邀您加入我们的翻译小组，成员主要来自计算机相关专业、英语专业和英文母语者。
 
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