Read more here: https://www.gnu.org/software/emacs/manual/html_node/emacs/Directory-Variables.html

The IPython Notebook is now known as the Jupyter Notebook (see http://ipython.org/notebook.html). Jupyter ignore values are already found in the Python.gitignore.

Added datasource folder

Official docs, found here:
https://intellij-support.jetbrains.com/hc/en-us/articles/206544839 (as
of 13 Aug 2016)

Apple renames OS X to macOS. Announced @ WWDC 2016

This file as documentation (which seems lacking) states is used for calling custom Maven goals from the IDE.
Ignoring this file was a source much confusion in few projects (mapping Run action to custom goals... etc etc) 
Also this file does anything worth ignoring
Added by #145
Exclusion of `nbactions.xml`  from `.gitgnore` should be discussed.

Visual Studio Code has a few files that can be placed into the workspace
in order to share settings across users.  Settings.json is for project
specific overrides.  Tasks.json is for executable tasks (build, gulp, etc.)
While launch.json is for debugging specific tasks.

.com.apple.timemachine.donotpresent is a system file created by TimeMachine on OSX by user choice.

Added auto-generated tag files.

These files differ on Windows and OS X.

Anything matched by `*.un~` will also be matched by the last rule, `*~`.

Code Recommenders introduced in Eclipse Luna (4.5) creates a .recommenders directory at the root of the workspace, like .metadata

The server-auth-dir is where Emacs stores authentication files for Emacs
servers (running over TCP). These are (usually) ephemeral in nature, and
should be ignored.

Just added some comments. Some of us don't need some of the lines in the file.

On systems that require a lib64, virtualenv creates a symlink to the local lib.

Remove .gradle because it is not eclipse specific and already added in Gradle.gitignore.

Add ignore for STS's .springBeans file

Added a forgotten IDE to the .gitignore documentation.

Why?
For completeness and correctness

What?
[Webstorm](https://www.jetbrains.com/webstorm).