Set tuning to psychovisual by default.

Also correct help message, now that it works for 4x4.

Author: tdaede

src/bin/common.rs

@@ -94,10 +94,10 @@ pub fn parse_cli() -> CliOptions {
         .default_value("false")
     ).arg(
       Arg::with_name("TUNE")
-        .help("Quality tuning (Will enforce partition sizes >= 8x8)")
+        .help("Quality tuning")
         .long("tune")
         .possible_values(&Tune::variants())
-        .default_value("psnr")
+        .default_value("Psychovisual")
         .case_insensitive(true)
     ).arg(
       Arg::with_name("PIXEL_RANGE")

src/encoder.rs

@@ -183,7 +183,7 @@ arg_enum!{
 
 impl Default for Tune {
   fn default() -> Self {
-    Tune::Psnr
+    Tune::Psychovisual
   }
 }