Implement setting of values to resolved QObject properties

After the resolution of a property, we can set it by index at run-time instead
of via name resolution.

Change-Id: I479599dabe343cf9e6582dcda12291aebfcce418
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Implement loading of resolved imported scripts

We can resolve the use of names that refer to imported scripts at compile
time and load them at run-time by index through context->importedScripts.

Change-Id: I681b19e7d68dbf3b9a68af00b4cea2a9254c2d78
Reviewed-by: Lars Knoll <lars.knoll@digia.com>