[BUG #6968] make @cldr a functor, to be consistent with other @-hints

- although we currently have not arguments for @cldr()
- but more consistent syntax
[BUG #6968] add support for @asset, @cldr

- use the same parsing for @require, @use, @asset and @cldr
[BUG #7390] allow complex type expressions in @type
[BUG #6968] integrated @asset, @cldr with old metaHints

- left @require, @use processing in MClassDependencies.dependencies_from_comphints
  (not sure if this could also be integrated in MClassHints.getHints?!)