Fix implicitly deleted move constructors (#1954)

These were incorrect and exhibited as warnings on more recent versions of
clang (notably on Mac).

- Use pointers instead of references internally in GenericHID and *Drive
- Leave PIDBase, PIDController, and Resource non-moveable
- Remove the atomic from m_disabled in NidecBrushless
- Make Timer and Trigger copyable as well as moveable
- Implement custom move constructor/assignment for SendableChooserBase

Also comment out some unused variables that caused clang warnings.

wpilibc/src/main/native/include/frc/GenericHID.h

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2008-2018 FIRST. All Rights Reserved.                        */
+/* Copyright (c) 2008-2019 FIRST. All Rights Reserved.                        */
 /* Open Source Software - may be modified and shared by FRC teams. The code   */
 /* must be accompanied by the FIRST BSD license file in the root directory of */
 /* the project.                                                               */
@@ -179,7 +179,7 @@ class GenericHID : public ErrorBase {
   void SetRumble(RumbleType type, double value);
 
  private:
-  DriverStation& m_ds;
+  DriverStation* m_ds;
   int m_port;
   int m_outputs = 0;
   uint16_t m_leftRumble = 0;