[modelica] Normalize invalid node ranges

Some files were parsed into ASTs with nodes having negative ranges.
For example:

package TestPackage
  package EmptyPackage
  end EmptyPackage;
end TestPackage;

has subtree:

  SimpleLongClassSpecifier "EmptyPackage"
    SimpleName "EmptyPackage"
    Composition
      ElementList <-- start = 3:3, end = 2:22
    SimpleName "EmptyPackage"

pmd-modelica/src/main/java/net/sourceforge/pmd/lang/modelica/ast/AbstractModelicaNode.java

@@ -66,6 +66,14 @@ abstract class AbstractModelicaNode extends AbstractNode implements Node, Modeli
         }
         endLine = parser.token.endLine;
         endColumn = parser.token.endColumn;
+
+        if (endLine < beginLine) {
+            beginLine = endLine;
+            beginColumn = endColumn;
+        }
+        if (endLine == beginLine && endColumn < beginColumn) {
+            beginColumn = endColumn;
+        }
     }
 
     @Override