Checking property consistency along connection instance does not work correctly

[lwrage]

Example model: AutonomousVehicleSystem from https://github.com/bisc/collision_detection_aadl.git
Instantiate system implementation avoidance_subsystem.impl in avoidance_subsystem.aadl
Connection instances have error markers about inconsistent latency value, but all values in the declarative model are identical.

[reteprelief]

The CacheThe default compares the objects. To fix some problems we added content comparison for certain cases (references and list of references and literals.
Need to add comparisons for int, real, range of int/real.

[lwrage]

We had overridden the equals method in property value classes to make this work. However this caused bug #524. In the fix we renamed the equals to sameAs(). This one needs to be used when checking property consistency.

[lwrage]

Values with units need to be converted to the same unit before comparison. Currently 2s != 2000ms.