Initial support for resolving meta-property access for the scope and context...

Initial support for resolving meta-property access for the scope and context objects at QML compile time

This avoids having to do a string lookup for ids and in the import cache at
run-time, before we can do a string hash lookup in the property cache. Instead
we resolve final properties in the context and scope object at compile time and
look them up at run-time using their index instead. The dependencies to these
properties are also tracked separately and recorded in the compiled data.

This is merely the initial patch. There's a lot left to do, such as having
specialized getter and setters for specific property types. Setters are missing
altogether right now and will fall back to name lookup.

Change-Id: If3cb4e7c9454ef4850a615f0935b311c9395b165
Reviewed-by: Lars Knoll <lars.knoll@digia.com>