1.20 update

Adds an optional feature which displays the contents of a bookshelf when left-clicked. Sneaking must be used to destroy the bookshelf when enabled.
Updates depreciated sign code.
Bumps the API version to 1.20
Builds against 1.20

src/test/java/net/knarcraft/bookswithoutborders/util/IntegerToRomanConverterTest.java

@@ -0,0 +1,40 @@
+package net.knarcraft.bookswithoutborders.util;
+
+import org.junit.Test;
+
+import static net.knarcraft.bookswithoutborders.utility.IntegerToRomanConverter.getRomanNumber;
+import static org.junit.Assert.assertEquals;
+
+/**
+ * A test class for IntegerToRomanConverter
+ */
+public class IntegerToRomanConverterTest {
+
+    @Test
+    public void basicNumbersTest() {
+        assertEquals("I", getRomanNumber(1));
+        assertEquals("II", getRomanNumber(2));
+        assertEquals("III", getRomanNumber(3));
+        assertEquals("IV", getRomanNumber(4));
+        assertEquals("V", getRomanNumber(5));
+        assertEquals("X", getRomanNumber(10));
+        assertEquals("XV", getRomanNumber(15));
+        assertEquals("XX", getRomanNumber(20));
+        assertEquals("L", getRomanNumber(50));
+        assertEquals("C", getRomanNumber(100));
+        assertEquals("D", getRomanNumber(500));
+        assertEquals("M", getRomanNumber(1000));
+    }
+
+    @Test
+    public void nineFourTest() {
+        assertEquals("IV", getRomanNumber(4));
+        assertEquals("IX", getRomanNumber(9));
+        assertEquals("XIV", getRomanNumber(14));
+        assertEquals("XIX", getRomanNumber(19));
+        assertEquals("XXIV", getRomanNumber(24));
+        assertEquals("XL", getRomanNumber(40));
+        assertEquals("IL", getRomanNumber(49));
+    }
+
+}