Changes in SysML-v2 language specification

[stevevestal]

I put a copy of the HARDENS *.sysml files into the Eclipse 2024-09 pilot tool and got lots of errors. Turns out the standard was modified a few months ago, “The visibility of an import is always shown explicitly by placing the keyword private, protected, or public before the import declaration.” Adding "public" for imports got rid of most of them (I recommend using "public" unless there is a reason to use "private"). There were still a few others, e.g., an interface def can only have two ends, not three. I added some comments, a diff should find those.

I will create a branch off the "developer" branch and put updated versions of the files in the specs/SysML folder.