Adds some helper functions to make getting direction-related values easier

Adds a function for getting the yaw given two locations
Adds a function for getting a block face given a yaw

src/test/java/net/knarcraft/stargate/utility/DirectionHelperTest.java

@@ -0,0 +1,33 @@
+package net.knarcraft.stargate.utility;
+
+import be.seeseemelk.mockbukkit.WorldMock;
+import org.bukkit.Location;
+import org.bukkit.World;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class DirectionHelperTest {
+
+    @Test
+    public void getYawFromLocationTest() {
+        World world = new WorldMock();
+        Location location1 = new Location(world, 100, 0, 100);
+        Location location2 = new Location(world, 100, 0, 101);
+
+        double yaw = DirectionHelper.getYawFromLocationDifference(location1, location2);
+        Assertions.assertEquals(0, yaw);
+
+        location2 = new Location(world, 100, 0, 99);
+        yaw = DirectionHelper.getYawFromLocationDifference(location1, location2);
+        Assertions.assertEquals(180, yaw);
+
+        location2 = new Location(world, 101, 0, 100);
+        yaw = DirectionHelper.getYawFromLocationDifference(location1, location2);
+        Assertions.assertEquals(270, yaw);
+
+        location2 = new Location(world, 99, 0, 100);
+        yaw = DirectionHelper.getYawFromLocationDifference(location1, location2);
+        Assertions.assertEquals(90, yaw);
+    }
+
+}