Fix memory leak with Coordinate::_lockFunction.

[chrisdembia]

I added a comment to the code to describe why I made this change:

This line was originally
in extendFinalizeFromProperties(), but this caused a memory leak since
extendFinalizeFromProperties() is called once when the model is
constructed from a file, and again when one calls Model::initSystem()
(or whenever finalizing from properties multiple times without recreating
the SimTK System).

By putting the allocation right next to the creation of the related PrescribedMotion, we should be able to avoid the leak.

I detected the leak in the process of trying to get testInitState to pass on OSX. I detected the leak with valgrind and also used valgrind to verify that the leak is now gone.

[chrisdembia]

@sherm1 says:

A nicer way to do this I think would be to use an std::unique_ptr to hold the freshly-allocated Function object until its ownership can be transferred to the PrescribedMotion constraint. It would look something like this:

std::unique_ptr<Function> func(new Function()); // func has ownership
ReferencePtr<Function> funcref(func.get()); // keep a reference to Function object
Constraint::PrescribedMotion(func.release()); // take over ownership from func

[chrisdembia]

To reviewers: please don't merge this until the above change is made. Also, feel free to make the above change for me!

[sherm1]

Also, feel free to make the above change for me!

OK, I did. Please review.

[sherm1]

Hmm. AppVeyor build died immediately; related to this morning's AppVeyor update? Chris, please see separate email.

[sherm1]

Added a commit to allow "deprecated-declaration" warnings to occur without error until we fix issue #528.

[sherm1]

I'm merging this now because it fixes the CI builds.

[chrisdembia]

Okay; @aseth1 definitely should look at these changes at some point.

[chrisdembia]

Thanks for doing this @sherm1 .