Test HTOA peak value against 0 (integer comparison)

Now whipper uses the absolute value of SoX's peak level as internal peak value.

Fixes #143.

whipper/result/logger.py

@@ -193,7 +193,7 @@ class WhipperLogger(result.Logger):
             lines.append("    Pre-gap length: %s" % common.framesToMSF(pregap))
 
         # Peak level
-        peak = trackResult.peak
+        peak = trackResult.peak / 32768.0
         lines.append("    Peak level: %.6f" % peak)
 
         # Pre-emphasis status

whipper/result/result.py

@@ -36,7 +36,7 @@ class TrackResult:
     filename = None
     pregap = 0  # in frames
     pre_emphasis = None
-    peak = 0.0
+    peak = 0
     quality = 0.0
     testspeed = 0.0
     copyspeed = 0.0