Rascal maven scheme lacks support qualifiers and `mavenize` has a problem with build numbers

[DavyLandman]

There is a clash between build numbers and qualifiers .

coordinate	path on disk	pom.xml
org.rascalmpl:rascal:0.40.0:jdk11	org/rascalmpl/rascal/0.40.0/rascal-0.40.0-jdk11.jar	org/rascalmpl/rascal/0.40.0/rascal-0.40.0.pom
org.rascalmpl:rascal:0.40.0-rc1	org/rascalmpl/rascal/0.40.0/rascal-0.40.0-rc1.jar	org/rascalmpl/rascal/0.40.0/rascal-0.40.0-rc1.pom

I think we need to support both classifiers and build numbers, and we can. but infering it from a file name is harder. The only way to detect it is looking at the pom.xml, that never has a classifier (by design). Or the parent directory.

So:

• the version 0.40.0 with qualifier jdk11 becomes |mvn://org.rascalmpl--rascal--0.40.0--jdk11/
• the version 0.40.0-rc1 becomes |mvn://org.rascalmpl--rascal--0.40.0-rc1/ (not the single dash)
• and the compbination would be |mvn://org.rascalmpl--rascal--0.40.0-rc1--jdk11/