made the switch to using bracket-lib directly, instead of rltk wrapper

this should solve the build issues; it makes using the non-crashing github build a lot easier, because it lets the explicit rltk dependency be removed.

src/ai/turn_status_system.rs

@@ -10,7 +10,7 @@ use crate::{
     Item,
     Prop,
 };
-use rltk::prelude::*;
+use bracket_lib::prelude::*;
 use specs::prelude::*;
 use crate::data::events::*;