* Added Blockchain Programming Book
* Added the packt link
* Added a Kotlin Playground
* The Kotlin Playground
* Added a Flutter Playground
* Removed the Leadin Slash
* Added Ruby Playground
* Added a new line at the end of free programming playgrounds
* Fixed the spacing in free-programming-books-fa_IR.md
* Fixed More errors in the above file
* Errors fixed in free-programming-books-fa_IR.md
* Some more changes
* Restored the previous farsi file
* Added an Elm Playground
* Added Blockchain Programming Book
* Added the packt link
* Added a Kotlin Playground
* The Kotlin Playground
* Added a Flutter Playground
* Removed the Leadin Slash
* Added Ruby Playground
* Added a new line at the end of free programming playgrounds
* Fixed the spacing in free-programming-books-fa_IR.md
* Fixed More errors in the above file
* Errors fixed in free-programming-books-fa_IR.md
* Some more changes
* Restored the previous farsi file
* Added Kaggle Python course
* Add Python Runestone to interactive tutorials
* added author
* Added Python and Java playground
* add space back
* lower cased name
* fixed capitalization for Java and JavaScript
* Added Rextester to R Interactive Playgrounds
* swapped order
* switched order
* Added Blockchain Programming Book
* Added the packt link
* Added a Kotlin Playground
* The Kotlin Playground
* Added a Flutter Playground
* Removed the Leadin Slash
* Add "What I Wish I Knew When Learning Haskell"
Follow up #3173.
* Update free-programming-books-zh.md
Follow up #3330.
* added competitive programming link
Follow up #3398.
* Update kotlin playground
The current kotlin playground is obsolete.
Updated to the new playground link.
* remove '/' to satisfy linter
Always check the Travis-CI output!
Co-authored-by: Eric Hellman <eric@hellman.net>
* Move a playground link to CSS section
FlexBox is a CSS feature.
This move is consistent with other files.
* Fix index in english free-programming-playgrounds
* Move a section according to alphabetical order
* Remove offline link pyfiddle.io
Shutdown confirmed: https://github.com/priyankcommits/pyfiddleio/issues/7
* Update free-programming-playgrounds.md
Added codesandbox.io under React (and removed the react reference from its listing on JavaScript).
Added a Java section and linked to repl.it
repl.it actually has sandboxes for most of the languages listed here, and maybe some others, but I didn't add them all in. The Swing support for Java is new, and has some bugs. They didn't respond to my report, so I think they are spread a little thin.
* add spaces to satisfy linter
* add space to satisfy linter
Co-authored-by: Eric Hellman <eric@hellman.net>
