[wpiutil] Split units.h into separate headers for each unit (#2551)

Closes #2508.

Co-authored-by: Prateek Machiraju <prateek.machiraju@gmail.com>

wpilibc/src/main/native/cpp/controller/RamseteController.cpp

@@ -9,6 +9,8 @@
 
 #include <cmath>
 
+#include <units/math.h>
+
 using namespace frc;
 
 /**

wpilibc/src/main/native/cpp/geometry/Rotation2d.cpp

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Copyright (c) 2019-2020 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.                                                               */
@@ -9,6 +9,7 @@
 
 #include <cmath>
 
+#include <units/math.h>
 #include <wpi/json.h>
 
 using namespace frc;

wpilibc/src/main/native/cpp/geometry/Translation2d.cpp

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Copyright (c) 2019-2020 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.                                                               */
@@ -7,6 +7,7 @@
 
 #include "frc/geometry/Translation2d.h"
 
+#include <units/math.h>
 #include <wpi/json.h>
 
 using namespace frc;

wpilibc/src/main/native/cpp/kinematics/DifferentialDriveWheelSpeeds.cpp

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Copyright (c) 2019-2020 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.                                                               */
@@ -7,6 +7,8 @@
 
 #include "frc/kinematics/DifferentialDriveWheelSpeeds.h"
 
+#include <units/math.h>
+
 using namespace frc;
 
 void DifferentialDriveWheelSpeeds::Normalize(

wpilibc/src/main/native/cpp/kinematics/MecanumDriveWheelSpeeds.cpp

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Copyright (c) 2019-2020 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.                                                               */
@@ -11,6 +11,8 @@
 #include <array>
 #include <cmath>
 
+#include <units/math.h>
+
 using namespace frc;
 
 void MecanumDriveWheelSpeeds::Normalize(

wpilibc/src/main/native/cpp/trajectory/Trajectory.cpp

@@ -7,6 +7,7 @@
 
 #include "frc/trajectory/Trajectory.h"
 
+#include <units/math.h>
 #include <wpi/json.h>
 
 using namespace frc;

wpilibc/src/main/native/cpp/trajectory/TrajectoryParameterizer.cpp

@@ -33,6 +33,8 @@
 
 #include <string>
 
+#include <units/math.h>
+
 using namespace frc;
 
 Trajectory TrajectoryParameterizer::TimeParameterizeTrajectory(

wpilibc/src/main/native/cpp/trajectory/constraint/CentripetalAccelerationConstraint.cpp

@@ -7,6 +7,8 @@
 
 #include "frc/trajectory/constraint/CentripetalAccelerationConstraint.h"
 
+#include <units/math.h>
+
 using namespace frc;
 
 CentripetalAccelerationConstraint::CentripetalAccelerationConstraint(

wpilibc/src/main/native/cpp/trajectory/constraint/DifferentialDriveVoltageConstraint.cpp

@@ -10,6 +10,7 @@
 #include <algorithm>
 #include <limits>
 
+#include <units/math.h>
 #include <wpi/MathExtras.h>
 
 using namespace frc;

wpilibc/src/main/native/cpp/trajectory/constraint/EllipticalRegionConstraint.cpp

@@ -9,6 +9,8 @@
 
 #include <limits>
 
+#include <units/math.h>
+
 using namespace frc;
 
 EllipticalRegionConstraint::EllipticalRegionConstraint(

wpilibc/src/main/native/cpp/trajectory/constraint/MecanumDriveKinematicsConstraint.cpp

@@ -7,6 +7,8 @@
 
 #include "frc/trajectory/constraint/MecanumDriveKinematicsConstraint.h"
 
+#include <units/math.h>
+
 using namespace frc;
 
 MecanumDriveKinematicsConstraint::MecanumDriveKinematicsConstraint(