Fix incorrect block progress calculation in header download log

  tip_height is 0-indexed, so the total header count is tip_height + 1.
  Using tip_height as the denominator caused >100% progress (e.g. 200%
  with 2 blocks) and division by zero when tip_height is 0.

  Fixes #197

Author: EddieHouston

src/daemon.rs

@@ -784,8 +784,8 @@ impl Daemon {
             info!(
                 "downloaded {}/{} block headers ({:.0}%)",
                 result.len(),
-                tip_height,
-                result.len() as f32 / tip_height as f32 * 100.0
+                tip_height + 1,
+                result.len() as f32 / (tip_height + 1) as f32 * 100.0
             );
         }