Allow teams extending a non-team class

[stephan]

By forcing org.objectteams.Team as the implicit super class of all teams, it is not possible for a team to inherit from any non-team class.

We might want to relax this rule by making org.objectteams.Team an interface plus moving the implementation to a new class org.objectteams.TeamImpl. If needed the compiler could just add (copy-inheritance) the required implementation into each team that cannot implicitly extend TeamImpl.

This issue came up when discussing the use of RMI for teams and roles, where extending UnicastRemoteObject is mandatory.

[stephan]

r23242 brings an initial experiment:

• I created a new interface org.objectteams.ITeam and let org.objectteams.Team implement it.
• Most references in generated code now use the interface rather than the class.

Reasons, why the class Team is still referenced

• it still holds the constant ALL_THREADS
• the compiler still treats class Team in special ways

[stephan]

The initial experiment entailed the following changes:

• r23244, r23245, r23246, r23247, r23248, r23249, r23250

With these tests are basically back to working.

r23251 increments the compiler version stored in class files to support minimal compatibility checks.

[stephan]

Basic implementation is in r23257, test is X.4.1-otjld-team-extends-regular-1.

TODO:

• more tests
• logic to control when to generate those methods/fields and when those are correctly inherited from a super team.

[stephan]

OTJLD has been changed in r23262.

As of r23271 only one (unavoidable) regression remains:

• 4.5.13-otjld-basecall-super-access-3, which tests for a binary compatibility we can no longer maintain

[stephan]

As of r23272 1.2.7-otjld-non-team-superclass-1 challenges further inheritance of an affected team and even a role played by the super class of its team: by way of r23273.

Closing as fixed.