Cleanup API for extending realize methods and for allowing users to realize the Component to the desired computational stage.
Rename non-virtual realize methods which also got renamed.
Merge branch 'master' into extendComponentRealizeMethods
implement non-virtual realize methods for Stage::Time through to Report.
Use the Component interface to realize the system in testComponentInterface.cpp
Add meaningful error message to Component::getSystem if system in null. This can only happen if the Component has not added itself to the system or if Model::initSystem() has not been called.
High level realization methods were removed from Component. It was agreed that only the top-level (aggregator) should have that ability to realize the system and only to provide access for scripting users.
The C++ API is complete since any Component including model provides getSystem() and realize(State, Stage) can be called directly on the system.

Added realize<Stage> methods to Model to provide access via scripting where the MultibodySystem and Stage are not wrapped.

These need to be tested via scripting.

An assortment of fixes to find and replace bugs that renamed realize<...> to extendRealize<...> in comments that were refering to the System methods and not virtual methods on Component.
Merge pull request #261 from opensim-org/extendComponentRealizeMethods

Extend component realize methods and addreses #184