client: add setters for selected spells and items (#1634)

* client: add setters for selected spells and items (thanks to Skitzo the absolute beast.)

* deob: change "changeSpellFlag" method name to "selectSpell"

* deob: export "selectSpell" for tests.

runescape-client/src/main/java/class83.java

@@ -20,7 +20,8 @@ public class class83 {
 	@ObfuscatedGetter(
 		intValue = 670190247
 	)
-	static int field1138;
+	@Export("selectedSpellWidget")
+	static int selectedSpellWidget;
 
 	static {
 		field1142 = new BigInteger("10001", 16);