PPM frame length set to (NUM_CHANNELS x 2ms + 5ms)

ChangeLog

 *0.4.2 ()
     added global setting to disable center/reset value beep
     minimum battery voltage set to 2V for those experimenting with 1S cell
-    PPM length shortened to "NUM_CHANNELS x 2ms + 4ms" to send new data
+    PPM length shortened to "NUM_CHANNELS x 2ms + 5ms" to send new data
 	to receiver as soon as possible
 
 *0.4.1 (17 Aug 2011)

ppm.c

@@ -43,7 +43,7 @@
 #define PPM_300US_SYNC ((PPM_MUL_SYNC * 3 + 5) / 10)
 
 // length of whole frame
-#define PPM_FRAME_LENGTH  (MAX_CHANNELS * 2000 + 4000)
+#define PPM_FRAME_LENGTH  (MAX_CHANNELS * 2000 + 5000)
 
 
 // channel variables