Shorten trace_readline_fields to trace_fields

* Per suggestion in #149

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>
diff --git a/examples/disksnoop.py b/examples/disksnoop.py
index 6da269b..aa16141 100755
--- a/examples/disksnoop.py
+++ b/examples/disksnoop.py
@@ -25,7 +25,7 @@
 
 # format output
 while 1:
-	(task, pid, cpu, flags, ts, msg) = b.trace_readline_fields()
+	(task, pid, cpu, flags, ts, msg) = b.trace_fields()
 	(bytes_s, bflags_s, us_s) = msg.split()
 
 	if int(bflags_s, 16) & REQ_WRITE: