adds damage types and mods (weak/resist/immune), for all damage events

tests/components_test.rs

@@ -0,0 +1,19 @@
+// tests/components_test.rs
+use rust_rl::components::*;
+
+#[test]
+fn damagetype_equality() {
+    let dt1 = DamageType::Physical;
+    let dt2 = DamageType::Physical;
+    assert_eq!(dt1, dt2);
+    let dt3 = DamageType::Magic;
+    assert_ne!(dt1, dt3);
+}
+
+#[test]
+fn damagetype_ismagic() {
+    let dt1 = DamageType::Physical;
+    let dt2 = DamageType::Magic;
+    assert!(!dt1.is_magic());
+    assert!(dt2.is_magic());
+}