Compact output, add -s color option, closes #70

Strip the empty lines within the results for each benchmark, but keep
the empty line between each benchmark, and before the summary.

Add `color` style option to show color but not be interactive (no
progress bar).

src/hyperfine/types.rs

@@ -71,6 +71,9 @@ pub enum OutputStyleOption {
 
     /// Keep elements such as progress bar, but use no coloring
     NoColor,
+
+    /// Keep coloring, but use no progress bar
+    Color,
 }
 
 /// Number of runs for a benchmark