Add out-of-the-box support for IntelliJ IDEA

[edvbld]

Hi all,

please review this PR that adds "out of the box" support for IntelliJ IDEA for
Skara. The changes primarily consists of:

• IntelliJ IDEA configuration files
• Re-working the build system to support one JRE for running Gradle and one JDK
  for building and testing Skara
• Documentation updates

The build changes are a bit messy, I will refactor them later, but I want to
await feedback first to see if we need to some additional changes.

Testing:

• Opening up the Skara root directory in a fresh install of IntelliJ IDEA on
  Linux x64

Thanks,
Erik

---

Progress

• Change must not contain extraneous whitespace
• Change must be properly reviewed

Download

$ git fetch https://git.openjdk.java.net/skara pull/489/head:pull/489
$ git checkout pull/489

[bridgekeeper]

👋 Welcome back ehelin! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request.

[mlbridge]

Webrevs

• 03: Full (9b23ff2)
• 02: Full - Incremental (44d746c)
• 01: Full - Incremental (79ab438)
• 00: Full (55500b7)

[bridgekeeper]

@edvbld This pull request has been inactive for more than 3 weeks and will be automatically closed if another 3 weeks passes without any activity. To avoid this, simply add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[openjdk]

@edvbld this pull request can no longer be integrated into master due to one or more merge conflicts. To resolve these merge conflicts and update this pull request you can run the following commands in the local repository for your personal fork:

git checkout intellij-idea
git fetch https://git.openjdk.java.net/skara master
git merge FETCH_HEAD
# resolve conflicts and follow the instructions given by git merge
git commit -m "Merge master"
git push

[bridgekeeper]

@edvbld This pull request has been inactive for more than 3 weeks and will be automatically closed if another 3 weeks passes without any activity. To avoid this, simply add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[bridgekeeper]

@edvbld This pull request has been inactive for more than 6 weeks and will now be automatically closed. If you would like to continue working on this pull request in the future, feel free to reopen it!