[Rev 01] RFR: Add out-of-the-box support for IntelliJ IDEA

[Erik Helin]

> 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

Erik Helin has updated the pull request incrementally with one additional commit since the last revision:

  Fix macOS build

-------------

Changes:
  - all: https://git.openjdk.java.net/skara/pull/489/files
  - new: https://git.openjdk.java.net/skara/pull/489/files/55500b72..79ab438c

Webrevs:
 - full: https://webrevs.openjdk.java.net/skara/489/webrev.01
 - incr: https://webrevs.openjdk.java.net/skara/489/webrev.00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/489.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/489/head:pull/489

PR: https://git.openjdk.java.net/skara/pull/489