* Updated `composer.phar` to latest version
* Remove libs that get installed by Composer from repo
(run `./composer.phar install` after checkout)
* Change `composer.json` to use default `vendor` dir and raise max. PHP
to 7.99.99 since we're at 7.4 now
* Rename `README.markdown` to `README.md`
This time, I deleted ckeditor/ckeditor/.git and removed everytjing before. I hope that the line in .gitignore will prevent the linking the next time if someone forgets to delete the file
