Implement Fetch and FetchFilter derive macros

Author: vladbat00

Cargo.toml

@@ -314,6 +314,10 @@ path = "examples/ecs/system_sets.rs"
 name = "timers"
 path = "examples/ecs/timers.rs"
 
+[[example]]
+name = "world_query"
+path = "examples/ecs/fetch.rs"
+
 # Games
 [[example]]
 name = "alien_cake_addict"