v5.0.0_stable version release

Some of the most important changes:

General
-------

- STM libs completely replaced by libopencm3
- [gcc-arm-embedded] (https://launchpad.net/gcc-arm-embedded) is the new recommended toolchain
- Use findlib (ocamlfind) for ocaml packages. Faster build.
  [#274] (https://github.com/paparazzi/paparazzi/pull/274)
- Building/Running the groundsegment on an ARM (e.g. RaspberryPi).
- Input2ivy uses SDL for joysticks (cross-platform, works on OSX as well now)
  [#220] (https://github.com/paparazzi/paparazzi/pull/220)
- Option to change text papget color using a combobox
  [#194] (https://github.com/paparazzi/paparazzi/pull/194)
- Redundant communications
  [#429] (https://github.com/paparazzi/paparazzi/pull/429)
- Log also contains includes like procedures now, so replay if these missions is possible.
  [#227] (https://github.com/paparazzi/paparazzi/issues/227)
- Paparazzi Center
    - New simulation launcher with dialog and detection of available ones.
      [#354] (https://github.com/paparazzi/paparazzi/pull/354)
    - Checkbox to print extra configuration information during build.
- GCS:
    - Fix panning with mouse if there are no background tiles.
      [#9] (https://github.com/paparazzi/paparazzi/issues/9)
    - Higher zoom level for maps.
      [#277] (https://github.com/paparazzi/paparazzi/issues/277)

Hardware support
----------------

- initial support for STM32F4
    - Apogee autopilot
    - KroozSD autopilot
- Parrot AR Drone 2 support: raw and sdk versions
- MS5611 barometer on Aspirin2.2
- CH Robotics UM6 IMU/AHRS
- GPS/INS XSens Mti-G support
- GPS Sirf support
- GPS Skytraq now usable for fixedwings as well
  [#167] (https://github.com/paparazzi/paparazzi/issues/167)
- Mikrokopter V2 BLDC
  [#377] (https://github.com/paparazzi/paparazzi/pull/377)
- PX4Flow sensor
  [#379] (https://github.com/paparazzi/paparazzi/pull/379)
- Dropped AVR support

Airborne
--------

- State interface with automatic coordinate transformations
  [#237] (https://github.com/paparazzi/paparazzi/pull/237)
- New AHRS filter: Multiplicative quaternion linearized Kalman Filter
- New SPI driver with transaction queues.
    - Fix transactions with zero length input.
      [#348] (https://github.com/paparazzi/paparazzi/issues/348)
- Peripherals: Cleanup and refactoring.
    - MPU60x0 peripheral supporting SPI and I2C with slave.
- UDP datalink.
- Magnetometer current offset calibration.
  [#346] (https://github.com/paparazzi/paparazzi/pull/346)
- Gain scheduling module.
  [#335] (https://github.com/paparazzi/paparazzi/pull/335)

Rotorcraft firmware specific
----------------------------

- Quadshot transitioning vehicle support.
- Care Free Mode