Fix Icon issue for IntelliJ 2020.1

[Koziolek]

Change old references to new that are recommended by documentation.

Happy Easter Eggs

Changelog

Enhancements

• Update build to IntelliJ IDEA 2020.1

Bug Fixes

• JetBrains IDEs 2020.1 compatibility
  • Change obsolete references to AllocIcons in Icons to new ones in AlllIcons that are recommended in documentation.
  • Update to @NotNull annotation on PsiElementVisitor
    • DepGatherer
    • QuotableImpl.quote

[emhagman]

Fixes #1654

[Koziolek]

@emhagman – I have some strange during build. Based on https://github.com/KronicDeth/intellij-elixir/blob/master/RELEASING.md but it is not working as expected.

[Koziolek]

@KronicDeth I made some extra changes to compile this stuff.

[Koziolek]

@emhagman my local build is here → http://koziolekweb.pl/Elixir-11.6.1-pre+20200410195935.zip
No guarantee that works fine and don't burn your machine.

[KronicDeth]

Official build is happening here

[KronicDeth]

Thanks for all your help @Koziolek ❤️

[nitingupta910]

Official build is happening here

It didn't go through, it seems.

[KronicDeth]

Huh, well that is interesting that it was build compilable, but not test compilable. That's why we have tests I guess. Investigating @nitingupta910

[Koziolek]

Fixed in #1744 but I'm not happy of that.

[nitingupta910]

Fixed in #1744 but I'm not happy of that.

IDE still doesn't see any plugin updates. No hurry but just want to let you know. Thanks.