Add MathUtils.clamp() for Java (#1861)

Also use std::clamp() and MathUtils.clamp() in as many places as
possible in place of custom clamp functions or if statements.

wpiutil/src/main/java/edu/wpi/first/wpiutil/math/MathUtils.java

@@ -0,0 +1,25 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+package edu.wpi.first.wpiutil.math;
+
+public final class MathUtils {
+  private MathUtils() {
+    throw new AssertionError("utility class");
+  }
+
+  /**
+   * Returns value clamped between low and high boundaries.
+   *
+   * @param value Value to clamp.
+   * @param low   The lower boundary to which to clamp value.
+   * @param high  The higher boundary to which to clamp value.
+   */
+  public static double clamp(double value, double low, double high) {
+    return Math.max(low, Math.min(value, high));
+  }
+}