Copter: update AC3.0-rc6 version and release notes

ArduCopter/ArduCopter.pde

@@ -1,6 +1,6 @@
 /// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
 
-#define THISFIRMWARE "ArduCopter V3.0.0-rc5"
+#define THISFIRMWARE "ArduCopter V3.0.0-rc6"
 /*
  *  ArduCopter Version 3.0
  *  Creator:        Jason Short

ArduCopter/ReleaseNotes.txt

@@ -1,5 +1,11 @@
 ArduCopter Release Notes:
 ------------------------------------------------------------------
+ArduCopter 3.0.0-rc6 16-Jun-2013
+Improvements over 3.0.0-rc5
+1) bug fix to Circle mode's start position (was moving to last loiter target)
+2) WP_ACCEL parameter added to allow user to adjust acceleration during missions
+3) loiter acceleration set to half of LOIT_SPEED parameter value (was hard-coded)
+------------------------------------------------------------------
 ArduCopter 3.0.0-rc5 04-Jun-2013
 Improvements over 3.0.0-rc4
 1) bug fix to LAND flight mode in which it could try to fly to mission's next waypoint location