Copter: update firmware version and release notes ahead of -rc2

ArduCopter/ArduCopter.pde

 /// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
 
-#define THISFIRMWARE "ArduCopter V3.0.0-rc1"
+#define THISFIRMWARE "ArduCopter V3.0.0-rc2"
 /*
  *  ArduCopter Version 3.0
  *  Creator:        Jason Short

ArduCopter/ReleaseNotes.txt

 ArduCopter Release Notes:
 ------------------------------------------------------------------
+ArduCopter 3.0.0-rc2 13-May-2013
+Improvements over3.0.0-rc1:
+1) smoother transition to waypoints, loiter:
+    reduced loiter max acceleration to smooth waypoints
+    bug fix to uninitialised roll/pitch when entering RTL, AUTO, LOITER
+2) fast waypoints - copter does not stop at waypoints unless delay is specified
+3) WPNAV_LOIT_SPEED added to allow faster/slower loiter repositioning
+4) removed speed limits on auto missions
+5) enhance LAND mission command takes lat/lon coordinates
+6) bug fix for RTL not pointing home sometimes
+7) centrifugal correction disabled when copter is disarmed to stop HUD moving
+8) centrifugal correction disabled when sat count less than 6 (AHRS_GPS_MINSATS)
+9) compass calibration reliability improvements when run from mission planner
+10) bug fix to allow compassmot to be run from mission planner terminal screen
+11) add support for H-quad frame
+12) add COMPASS_ORIENT parameter to support external compass in any orientation
+------------------------------------------------------------------
 ArduCopter 3.0.0-rc1 01-May-2013
 Improvements over 2.9.1b:
 1) Inertial navigation for X & Y axis (Randy/Leonard/Jonathan)