Delete Book which not free now

* Replace homepage with GitHub repository link

problem-sets-competitive-programming.md: Replace homepage
link of problembook with github repository link which contains
downloadable pdf links.

* Remove broken links

Remove broken links and update available links from
web.archive.org.

* Update broken link with updated link.

Update the description for the updated link.

* Update broken links with links from web.archive.org

Remove dead links.

* Restore path to original link instead of web.archive.org

The link seems to be working fine. It was not loading
on my network, probably due to regional restrictions.

* Remove github link which is no longer maintained.

Github link consisted of list of Big Data resources.
The repository has been deleted by the user.
Hence deleting the entry.

* Update free-programming-books-zh.md

* added back blank line to satisfy the linter

* add two books in `-zh` list in `Python` section

* https -> http on explore-python link

* the old site has not update so this is the new one

* remove trailing slash from url to satisfy travis

* 添加正则表达教程

* Update free-programming-books-zh.md

* 1. Domain name http://reactjs.cn was sold and it is not related to react js for now. So I change it to another available site.

2. Tweak React to React.js

* fix ordering

Thanks for the contribution!
* add three book in free-programming-books-zh.md `Python` section

* order of adjustment

* remove the book in english and add author

* add PHP composer zh doc and laravel zh doc

add PHP composer zh doc and laravel zh doc

* add Vue.js zh doc

* add chinese PSR,Yii,Phalcon doc

PSR is PHP Standard Recommendations.Yii and Phalcon is PHP Framework.

* Sort by unicode

* Sort by unicode

```php
public function utf8_array_asort(&$array) {
        if (!isset($array) || !is_array($array)) {
            return false;
        }
        foreach ($array as $k => $v) {
            $array[$k] = iconv('UTF-8', 'GBK//IGNORE', $v);
        }
        asort($array);
        foreach ($array as $k => $v) {
            $array[$k] = iconv('GBK', 'UTF-8//IGNORE', $v);
        }

        return true;
    }
```

* sort by remark-lint-alphabetize-lists

* Fix travis-ci warning

@52fhy Thanks for being a contributor to F-P-B! Next time, remember to check the Travis CI output, it makes it much easier for the maintainers.

* Update PHP and Shell.

* update python and php

* update shell

* fix number of blank lines between sections

* 添加 Ruby on Rails Guide

添加 Ruby on Rails 简体中文指南

* add a line

* change order

* remove tailing slash

* add sinatra link

* add: 计算机图形学

* code review

* code lint

* Update broken links

* Add pdf indication

* Update broken links

* Small fix

* Update broken link

* Remove problematic links

* Fix according to comments

* Formatting

增加一个在线教育网站。

* Update free-programming-books-zh.md

* Update free-programming-books-zh.md

* Fix the anchor can't click（To free-programming-books-zh）

* Angular Course added closes #1690

* Inroduction to Rx closes #1817

* Overwork on free-prpgramming-books-zh.md

* Done #1948

* Deleted not-freely obtainable ebook closes #1930