See this SO post: https://stackoverflow.com/questions/49557737/should-i-add-idea-caches-build-file-checksums-ser-to-gitignore

and this Google issue tracker ticket: https://issuetracker.google.com/issues/77544553

for justification.

contentModel.xml is automatically generated and can be safely ignored.

Source: https://rider-support.jetbrains.com/hc/en-us/community/posts/115000661950-A-lot-of-files-in-contentModel-xml?page=1#community_comment_115000538984

Add extra commented section to use when using Gradle or Maven auto-import.
These are mentioned in the original reference for optional excludes (https://intellij-support.jetbrains.com/hc/en-us/articles/206544839).
If this would be better as a separate, non-commented ignore file, let me know and I will resubmit.

.idea/misc.xml used to contain usage statistics.  This was broken out to usage.statistics.xml in the latest EAP (2018.2 EAP).  It should be excluded from git.

See https://youtrack.jetbrains.com/issue/IDEA-192913

ignore dbnavigator.xml

because it contains sensitive data, such as host, port, db, user name, and so on.

This directory used by HTTP Client in IntelliJ IDEA (and other product).
https://www.jetbrains.com/help/idea/http-client-in-product-code-editor.html#viewingResponse

Since IDEA 14 (2014), IDEA and other contemporaneous JebBrains IDEs don't store sensitive info in `datasources.xml` and it makes sense to version control to share project data sources among the team. `dataSources.local.xml` is user-specific: contain usernames and could be sensitive from a security perspective, albeit passwords could be externalized to e.g. Mac Keychain.

References: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839, https://youtrack.jetbrains.com/issue/IDEA-127105

On line 1, WebStorm is capitalized the same way as the other IDE names.

- Ignore all cmake build directories, not just debug.

**Reasons for making this change:**

The file `replstate.xml` contains the history of the Clojure REPL
that Cursive adds to IntelliJ. Obviously that's user-specific,
and not relevant to other users.

**Links to documentation supporting these rule changes:**

This file is not well-documented, but in cursive-ide/cursive#1325,
the Cursive developers state that this is the REPL history file,
and that deleting it is acceptable troubleshooting if it's
causing trouble.

In newer versions of the IntelliJ platform (such as the one used for Rider), the .idea files are now placed in a subdirectory of the same, named after the current project (such as ".idea/.idea.Everlook/.idea/workspace.xml"). Adding a double-star pattern to these folder rules will also ignore these new files and maintain backwards compatibility with previous revisions of this file.

Added datasource folder

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

These files differ on Windows and OS X.

Added a forgotten IDE to the .gitignore documentation.

Why?
For completeness and correctness

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

Since that is what it should be called now a days according to https://dev.twitter.com/fabric/android/integrating

which make it easier to find in search

JetBrains recently released a new C/C++ IDE: CLion

Intellij's iml file can be anywhere on the path.
This is true for multi-module maven project where each module has its own $projectName.iml file in its own directory.

These are relatively new, the crashlytics.properties file contains the secret and can [alternatively](https://plus.google.com/+AntonioBertucci/posts/S9krjvXfgfm) contain the apikey to rid your repo of the extra strings file.

Amends #1165