Copter: add PILOT_TKOFF_ALT_DEFAULT definition

No functional change

ArduCopter/Parameters.pde

@@ -78,7 +78,7 @@ const AP_Param::Info var_info[] PROGMEM = {
     // @Units: Centimeters
     // @Range: 0.0 1000.0
     // @Increment: 10
-    GSCALAR(pilot_takeoff_alt,  "PILOT_TKOFF_ALT",     0.0f),
+    GSCALAR(pilot_takeoff_alt,  "PILOT_TKOFF_ALT",  PILOT_TKOFF_ALT_DEFAULT),
 
     // @Param: PILOT_TKOFF_DZ
     // @DisplayName: Takeoff trigger deadzone

ArduCopter/config.h

@@ -367,6 +367,17 @@
  # define FS_THR_VALUE_DEFAULT             975
 #endif
 
+//////////////////////////////////////////////////////////////////////////////
+// Takeoff
+//
+#ifndef PILOT_TKOFF_ALT_DEFAULT
+ # define PILOT_TKOFF_ALT_DEFAULT           0     // default final alt above home for pilot initiated takeoff
+#endif
+
+
+//////////////////////////////////////////////////////////////////////////////
+// Landing
+//
 #ifndef LAND_SPEED
  # define LAND_SPEED    50          // the descent speed for the final stage of landing in cm/s
 #endif