Simplify code a bit (suggestions by clippy)

src/main.rs

@@ -405,11 +405,11 @@ fn run() -> Result<ExitCode> {
         exclude_patterns: matches
             .values_of("exclude")
             .map(|v| v.map(|p| String::from("!") + p).collect())
-            .unwrap_or_else(|| vec![]),
+            .unwrap_or_else(Vec::new),
         ignore_files: matches
             .values_of("ignore-file")
             .map(|vs| vs.map(PathBuf::from).collect())
-            .unwrap_or_else(|| vec![]),
+            .unwrap_or_else(Vec::new),
         size_constraints: size_limits,
         time_constraints,
         #[cfg(unix)]

src/output.rs

@@ -4,7 +4,6 @@ use std::process;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 
-use ansi_term;
 use lscolors::{LsColors, Style};
 
 use crate::exit_codes::ExitCode;