AP_Scheduler: added current_task static

will be used to debug stuck tasks on PX4
HAL_PX4: print overtime message on stuck task

this should make it easier to narrow down stuck task bugs
GPS: Include 75-class CPUs in RTK support since they will have 64 bit floating point values.
GPS: Fix dataflash logging bug in SBP driver
AP_HAL_VRBRAIN: removed empty lines
PX4: disable PX4IO RC handling in a clean way

Upstream PX4 Firmware provides a clean way to disable PX4IO handling by supplying the argument "norc" to "px4io start". After applying this fix to the rc.APM startup script, the quick hack contained in commit 180cceee of diydrones/PX4Firmware can be safely reverted.
AP_Common: added fire cape product ID
AP_InertialSensor_MPU9150: I2C userspace driver sensor added.

The MPU9150 is a 9 axis sensor that includes 3 accelerometers,
3 gyroscopes and 3 magnetometers. All accessible through I2C.
The AP_InertialSensor_MPU9150 class allows APM to use this sensor.
HAL_BOARD_ERLE: new abstraction layer, Erle Robot

A layer for the OS/OW Erle Robot quadcopter has been
created. For now the robot relies on the AP_HAL_LINUX
layer.
L3G4200D: fix in the test example provided.

The test coded had a call to "wait_for_sample" that expected one
argument and 0 where provided.
AP_HAL_Linux: SPIDriver, add MPU6000 support
APM_Config.h: Enable the CLI by default.
config.h: disable the MAGNETOMETER in the Erle HAL
AP_HAL: Add SPIDevice_MPU9250 as a device.
AP_HAL_Linux: Add support for SPIDevice_MPU9250

The Invensense MPU9250 SPI device is connected to
SPI1, thereby SPIDriver class should return the
corresponding device.
AP_InertialSensor_MPU9250: SPI userspace sensor driver.

InvenSense MPU9250 sensor driver and test code (available under
libraries/examples/).
AP_HAL_Linux_Class: Correct deadlock, and infinite loop in setup()

(credit to Mitch Miers <mmiers@mmiers.com>):

setup() is attempting to initialize the hardware, and while doing so
is attempting to output some text via the console (and maybe mavlink
data).  The problem is, the output isn't going to complete once a
write buffer is full, because LinuxUARTDriver::_timer_tick() doesn't
perform work until _initialized is true.  So, what happens is,
setup() (and subroutines) call LinuxUARTDriver::_write(uint8_t c),
which loops waiting for buffer space to become available (once the
write buffer is full).  The buffer never gets space, because the
UART thread is waiting for initialization to complete before it
will write out data and drain the buffer, but that doesn't happen
until setup() returns (see AP_HAL_Linux_main.h).

Refer to https://groups.google.com/forum/#!topic/beaglepilot/dQlxse11JNI
APM_Config: Add configurations to the ERLE_BOARD_HAL
AP_Baro_MS5611: Fix the test code so that compiles.

Add HAL_BOARD_LINUX and HAL_BOARD_ERLE compatibility.
AP_InertialSensor_MPU6000: Fix the test code so that compiles.