AutoTest: adjust copter CIRCLE_RADIUS to 3000
AC_PID: results returned as float
AC_PID: add AC_P controller

Used for stabilize angle controllers, alt hold and loiter
AC_WPNav: remove AC_PID include

This is no longer required with introduction of PosControl lib
AC_Circle: remove AC_PID include

This is no longer required with introduction of PosControl lib
AC_PosControl: replace APM_PI with AC_P
AC_AttControl: replace APM_PI with AC_P
AC_AttControlHeli: replace APM_PI with AC_P
Copter: replace APM_PI with AC_P

Saves about 90bytes of RAM
AC_AttControl: fix example sketch
AC_Fence: fix example sketch
AC_Sprayer: fix example sketch
AC_WPNav: fix example sketch
HAL_AVR: ArduCopterLibs to use AC_P library
AC_INav: fix example sketch
AP_Motors: fix example sketch
Baro: fix BMP085 example sketch
AP_Airspeed: fix example sketch
AP_AHRS: fix example sketch