VS Code/Codium extension for flux

[katauber]

New Xtext project with copy of flux grammar file to provide a language server, which is used for a VS Code/Codium Extension.

[fsteeg]

Nice, this looks good in codium! With the syntax coloring for comments, operators etc.

Noticed one minor thing: .checkstyle contains a machine-specific path. In the root, I don't think we actually need that file at all (the Eclipse Checkstyle plugin should pick up the config using the project-specific file like org.metafacture.flux.ide/.checkstyle, which uses a relative path).

As in metafacture-fix, we should also generate Java sources instead of Xtend. I was thinking of opening a separate issue for that, but maybe it makes sense to do that here, before checking in any Xtend sources in the first place. See metafacture/metafacture-fix@7b8863d for the setup and metafacture/metafacture-fix@4be8950 for the resulting code changes in metafacture-fix.

[katauber]

Thank you for the feedback. I deleted the checkstyle file in the root and I changed to Java resources instead of XTend resources.

[fsteeg]

Great, thanks. Merging, will assign metafacture/metafacture-fix#21 for functional review.