Added 'none' as a possible value for "style" option

This commit allows to remove all non-errornous output of the tool.

src/main.rs

@@ -55,6 +55,7 @@ fn main() {
     let options = build_hyperfine_options(&matches);
     let export_manager = build_export_manager(&matches);
     let commands = build_commands(&matches);
+    let unwrapped_opts = options.unwrap();
 
     let res = match options {
         Ok(ref opts) => run(&commands, &opts),
@@ -63,8 +64,8 @@ fn main() {
 
     match res {
         Ok(timing_results) => {
-            write_benchmark_comparison(&timing_results);
-            let ans = export_manager.write_results(timing_results, options.unwrap().time_unit);
+            if unwrapped_opts.output_style != OutputStyleOption::None { write_benchmark_comparison(&timing_results); }
+            let ans = export_manager.write_results(timing_results, unwrapped_opts.time_unit);
             if let Err(e) = ans {
                 error(&format!(
                     "The following error occurred while exporting: {}",
@@ -135,6 +136,7 @@ fn build_hyperfine_options(matches: &ArgMatches<'_>) -> Result<HyperfineOptions,
         Some("basic") => OutputStyleOption::Basic,
         Some("nocolor") => OutputStyleOption::NoColor,
         Some("color") => OutputStyleOption::Color,
+        Some("none") => OutputStyleOption::None,
         _ => {
             if !options.show_output && atty::is(Stream::Stdout) {
                 OutputStyleOption::Full