Change name of implicit root containments

[larsk21]

When explicitly (or currently also implicitly, see #134) creating a root class, the implicitly created containment references from the root class to other, non-contained classes are named allXs (e.g., allMovies for a class Movie). Instead, we could name them xs (e.g., movies), which is a bit nicer to read. The relevant definition is:

NeoJoin/lang/frontend/language/src/main/java/tools/vitruv/neojoin/Constants.java

Line 9 in 15b7d01

public static final String RootReferenceNameFormat = "all%ss";

Also, it is a bit weird that NeoJoin complains that queries without a source section (such as create root MyRoot ...) must have a body, but when explicitly specifying an empty body (create root MyRoot {}), the references to non-contained classes are still generated. Maybe we should just allow queries without a source section and without a body.

[larsk21]

Also, it is a bit weird that NeoJoin complains that queries without a source section (such as create root MyRoot ...) must have a body, but when explicitly specifying an empty body (create root MyRoot {}), the references to non-contained classes are still generated. Maybe we should just allow queries without a source section and without a body.

After re-considering this point, the current behavior does make sense, as a missing body, in contrast to an empty body, implies that all features are copied from the source class. If we define a root class without a source class, we therefore should have a, potentially empty, body. The additionally created implicit containment references are still not visible, but I guess that is just the semantics of the root keyword then.