Coordinate state variable names fixes #135

Address issue #135 and give the coordinate state variable suitable names. These are currently "value" and "speed". The full names are "<coordinateName>/value"  and "<coordinateName>/speed". This change re-exposed numerous frailties in how OpenSim establishes correspondence between values in files and state variables belonging to Components and the underlying State.  These include having multiple places were this "correspondence" is being established (e.g. `Model::fromCompleteStorage()`, `SimbodyEngine::formCompleteStorages()`, and "CMC_TaskSet::setFunctions()` to name a few. Other issues include performing the look-up within a computational method, e.g. `StaticOptimizationTarget::computeConstraintVector()` that is called thousands of times during an optimization. These should be addressed by future PRs.