Makes a whole lot of changes

Adds some new tests
Improves plugin command handling by using one class for each command
Makes some changes to vehicle teleportation to support horses and pigs, but vehicle teleportation is still buggy and messy
Adds some more missing comments
Adds a wildcard permission and uses built-in permissions some places to avoid checking for three different permissions

src/test/java/net/knarcraft/stargate/BlockLocationTest.java

@@ -81,4 +81,13 @@ public class BlockLocationTest {
         assertEquals("56,87,34", location.toString());
     }
 
+    @Test
+    public void modRelativeTest() {
+        BlockLocation location = new BlockLocation(mockWorld, 5, 5, 5);
+        BlockLocation relativeLocation = location.modRelative(4, 2, 1, -1, 1, 0);
+        assertEquals(9, relativeLocation.getBlockX());
+        assertEquals(3, relativeLocation.getBlockY());
+        assertEquals(6, relativeLocation.getBlockZ());
+    }
+
 }

src/test/java/net/knarcraft/stargate/RelativeBlockVectorTest.java

@@ -0,0 +1,17 @@
+package net.knarcraft.stargate;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class RelativeBlockVectorTest {
+
+    @Test
+    public void getTest() {
+        RelativeBlockVector relativeBlockVector = new RelativeBlockVector(56, 44, 23);
+        assertEquals(56, relativeBlockVector.getRight());
+        assertEquals(44, relativeBlockVector.getDepth());
+        assertEquals(23, relativeBlockVector.getDistance());
+    }
+
+}