fix tests
Module dependencies: correctly restore dependency scope when reading from descriptor file (defect).
Module dependencies: do not use EXTENDS dependency between languages for the sake of inclusion of runtime solution at compile time. Instead, dedicated GENERATES_INTO is supported, to denote dependency between the languages, when one of them is generated into another.
Module dependencies: drop extends of smodel language in favor of more specific 'generation target' dependency.
GeneratorValidator: use single dependency source instead of duplicating code which analyses available runtime dependencies.
Update build script to reflect generator language no longer extends lang.smodel