Having PCM as a singleton is a problem, as multiple things need to use it, and that gets really ugly. This changes PCM's to be a reference counted object, that can be passed around and constructed from multiple places.
In Java, this is using a map to hold a data store with a ref count, and allocating new objects any time a duplicate is requested.
In C++, this uses a trick constructor to store a PCM instance in the data store itself. This instance can then be passed to base objects using std::shared_ptr's aliasing constructor, which means constructing a solenoid from a PCM is not allocating after the 1st one.
This did require removing sendable from PCM. A compressor class was added back in to act as sendable for the PCM.
After this change is finished, the only change RobotBuilder and Team Code would require is passing a module type to solenoid constructors.
Co-authored-by: sciencewhiz <sciencewhiz@users.noreply.github.com>
This is the C++ version of #1682.
The old command framework is still available, but will be deprecated.
Due to name conflicts, the new framework is in the frc2 namespace.
Eventually (after the old command framework is removed in a future year)
it will be moved into the main frc namespace.
