Fixes several bugs and problems

Fixes getting the name of enchantments
Fixes inconsistencies in material and enchantment name-checking
Allows using "null" or "-1" to unset per-material or per-enchantment configuration options
Fixes a bug where basePrice was set to a material name instead of the price for the material being displayed
Adds missing tab-completion for material/enchantment costs
Prevents inconsistencies in deciding if a value is null

src/main/java/net/knarcraft/blacksmith/util/InputParsingHelper.java

@@ -13,6 +13,17 @@ public final class InputParsingHelper {
 
     }
 
+    /**
+     * Gets whether the input is an "empty" value treated as null
+     *
+     * @param input <p>The input to check</p>
+     * @return <p>True if the value is empty</p>
+     */
+    public static boolean isEmpty(String input) {
+        return input == null || input.equalsIgnoreCase("null") || input.equals("\"\"") ||
+                input.trim().isEmpty() || input.equals("-1");
+    }
+
     /**
      * Tries to find the material matching the given input string
      *