[BUG #7270] minor comment
[BUG #7270] moved compile-time lint checking to CodeGenerator

- removed lint code from MClassCode, MClassDependencies
- add a suitable api ("lint_classes") in CodeMaintenance, which should be
  usable for all high-level actions (runCompiled, runDependencyLogging, ...)
- removed unnecessary 'if' check for build-type in CodeGenerator
minor doc
minor doc