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/random_table.rs

@@ -1,4 +1,4 @@
-use rltk::RandomNumberGenerator;
+use bracket_lib::random::RandomNumberGenerator;
 
 // FIXME: note to self,
 // passing around strings here is super inefficient, so this is