Use binary prefixes for size and rate units

Includes adding support for additional size input suffix Mi and MiB, treated equivalent to M.
Extends binary suffix output with letter i, e.g. Ki and Mi.
Centralizes creation of bit/byte unit strings.

backend/opendrive/opendrive.go

@@ -88,7 +88,7 @@ func init() {
 
 Note that these chunks are buffered in memory so increasing them will
 increase memory use.`,
-			Default:  10 * fs.MebiByte,
+			Default:  10 * fs.Mebi,
 			Advanced: true,
 		}},
 	})