fix warnings about trivial casts, mostly {i,u}128 -> {i,u}128, such as "i128::min_value() as i128"

clippy_lints/src/lib.rs

@@ -9,7 +9,7 @@
 #![recursion_limit = "256"]
 #![feature(macro_at_most_once_rep)]
 #![feature(tool_lints)]
-#![warn(rust_2018_idioms)]
+#![warn(rust_2018_idioms, trivial_casts, trivial_numeric_casts)]
 #![feature(crate_visibility_modifier)]
 
 use toml;