Adds various improvements, fixes and a new feature

Adds and option to match any paid sign condition instead of all conditions
Adds checks for whether line indices are outside the allowed range
Disallows any invalid regular expressions in sign conditions

src/main/java/net/knarcraft/paidsigns/formatting/TranslatableMessage.java

@@ -115,4 +115,9 @@ public enum TranslatableMessage {
      */
     ERROR_CANNOT_AFFORD,
 
+    /**
+     * The error to display if an invalid regular expression is provided
+     */
+    ERROR_INVALID_REGULAR_EXPRESSION,
+
 }