Clean up drive class implementations

Left and right sides of the differential drive and mecanum drive classes
are now both forward and the "inversion multiplier" was removed.

The deadband functionality was moved to GenericHID::GetRawAxis() since
the deadband is generally applied to joystick axes.

MotorSafety was removed since that's handled by the drivetrain's motor
controllers already.

RobotDrive was removed because it's been deprecated for several years
and was only used in tests.

wpilibc/src/main/native/cpp/GenericHID.cpp

@@ -1,12 +1,14 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2016-2018 FIRST. All Rights Reserved.                        */
+/* Copyright (c) 2016-2019 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.                                                               */
 /*----------------------------------------------------------------------------*/
 
 #include "frc/GenericHID.h"
 
+#include <cmath>
+
 #include <hal/HAL.h>
 
 #include "frc/DriverStation.h"
@@ -34,7 +36,7 @@ bool GenericHID::GetRawButtonReleased(int button) {
 }
 
 double GenericHID::GetRawAxis(int axis) const {
-  return m_ds.GetStickAxis(m_port, axis);
+  return ApplyDeadband(m_ds.GetStickAxis(m_port, axis), m_deadband);
 }
 
 int GenericHID::GetPOV(int pov) const { return m_ds.GetStickPOV(m_port, pov); }
@@ -83,3 +85,17 @@ void GenericHID::SetRumble(RumbleType type, double value) {
   }
   HAL_SetJoystickOutputs(m_port, m_outputs, m_leftRumble, m_rightRumble);
 }
+
+void GenericHID::SetAxisDeadband(double deadband) { m_deadband = deadband; }
+
+double GenericHID::ApplyDeadband(double value, double deadband) {
+  if (std::abs(value) > deadband) {
+    if (value > 0.0) {
+      return (value - deadband) / (1.0 - deadband);
+    } else {
+      return (value + deadband) / (1.0 - deadband);
+    }
+  } else {
+    return 0.0;
+  }
+}