[PlutoLib] Added the ConstantExpression annotation, added annotations for readability

UPDATE_NOTES.md

@@ -3,10 +3,13 @@
 * `[PlutoLib]` Removed `TextIn`, `TextOut`, `ResourceImage` and `ResourceInputStream`
 * `[PlutoLib]` Made `OutputSplitStream` public as it is now reusable
 * `[PlutoLib]` Added the `@ConstantExpression` annotation
-* `[PlutoLib]` Moved `cz.tefek.pluto.io.pluto.pp` to `cz.tefek.pluto.io.plutopackage`
 * `[PlutoLib]` The `RAID#getIDOf` method now returns `OptionalInt` to avoid NPEs
 * `[PlutoLib]` The transitive dependency JOML is now provided by `PlutoLib` instead of `PlutoStatic`
 
+Awaiting implementation:
+* `[PlutoLib]` Moved `cz.tefek.pluto.io.pluto.pp` to `cz.tefek.pluto.io.plutopackage`
+* `[PlutoLib]` Completely reworked the module system
+
 ## 20.2.0.0-alpha.2
 * `build.gradle` Extracted the version numbers into separate variables
 * `build.gradle` **[experimental]** `gradlew` should now automatically download JDK11 when needed 

plutolib/src/main/java/cz/tefek/pluto/annotation/ConstantExpression.java

@@ -0,0 +1,22 @@
+package cz.tefek.pluto.annotation;
+
+import javax.annotation.meta.TypeQualifier;
+import java.lang.annotation.*;
+
+/**
+ * Denotes that the target field or method should be a constant expression - it is final, has no state
+ * and always yields the same deterministic result for given input. Generally, annotated methods
+ * should be thread-safe, however this is not required.
+ *
+ * @author 493msi
+ *
+ * @since 20.2.0.0-alpha.3
+ * */
+@TypeQualifier
+@Documented
+@Retention(RetentionPolicy.CLASS)
+@Target({ ElementType.METHOD, ElementType.FIELD })
+public @interface ConstantExpression
+{
+
+}

plutolib/src/main/java/cz/tefek/pluto/io/asl/resource/raid/RAID.java

@@ -21,7 +21,7 @@ public class RAID<E extends IIdentifiable> implements Iterable<E>
         this.reverseRaid = new HashMap<>();
     }
 
-    public void register(E item)
+    public void register(@Nonnull E item)
     {
         var address = item.getStringID();
 
@@ -48,7 +48,7 @@ public class RAID<E extends IIdentifiable> implements Iterable<E>
     }
 
     @Nonnull
-    public OptionalInt getIDOf(E item)
+    public OptionalInt getIDOf(@Nonnull E item)
     {
         return reverseRaid.containsKey(item.getStringID()) ?
             OptionalInt.of(reverseRaid.get(item.getStringID()))