[nps] don't bypass ahrs by default

By default use the result of the normal ahrs estimation,
if you want to bypass that and use the attitude from NPS define NPS_BYPASS_AHRS to TRUE.
[rotorcraft][messages] GUIDANCE_H_INT message
[airframes] update GUIDANCE_H gains for quadrotor example
Merge branch 'master' into ahrs_int_cmpl_quat_correction_scaling

relevant fixes/features from master:
- don't bypass normal ahrs estimation in NPS by default
- use horizontal guidance ref by default (and for HOVER mode)
- abs(c_route) and abs(s_route) instead of abs(route) in north and east route components calculation
- guidance_h gains for Quad_LisaM_2 example
[stm32] Fixes for USART interrupt handler.

The interrupt handler occasionally hangs in case of noise on the line.
Fixes were two:
1) Disable IDLE line interrupt, disable LIN break interrupt in the port settings.
   (neither of them should be used for asynchronous single buffer communication).
2) In interrupt handler routine, explicitly check for the error flags, only if
   no errors occur check the received byte. Otherwise clear the USART_DR and
   log the error.

Added USART_ERRORS messages to monitor problems on USART lines.

Closes #418
[rotorcraft] silence warning in guidance
[rotorcraft] alternate buses when sending I2C_ERRORS message
[makefile] fix sim build on OS X after broken from no_custom, can't seem to build the autopilot.so properly so back to -custom just for simsitl
[Makefile] improve detection of lablgtk2-gnome.*
[rotorcraft] Add forward mode for transitioning vehicles
[rotorcraft] TRANSITION_MAX_OFFSET in radians, float fixes
[Makefile] use -fPIC for all architectures
[umarim] remove warning if no mag are used with umarim
[tcas] tcas always runs on AP. Proposed solution for compile error.
[ext] update libopencm3 to get 16MHz resonator clock for F4
[uart] uart4 and 6 on stm32f4, generic set function (used on uart1)
[stm32] set_uart_pin only for F4
Merge remote-tracking branch 'paparazzi/mpu60x0' into stm32f4
Merge branch 'master' into stm32f4

* master: (31 commits)
  [tcas] tcas always runs on AP. Proposed solution for compile error.
  [umarim] remove warning if no mag are used with umarim
  [Makefile] use -fPIC for all architectures
  [rotorcraft] TRANSITION_MAX_OFFSET in radians, float fixes
  [rotorcraft] Add forward mode for transitioning vehicles
  [Makefile] improve detection of lablgtk2-gnome.*
  [makefile] fix sim build on OS X after broken from no_custom, can't seem to build the autopilot.so properly so back to -custom just for simsitl
  [rotorcraft] alternate buses when sending I2C_ERRORS message
  [rotorcraft] silence warning in guidance
  [stm32] Fixes for USART interrupt handler.
  [airframes] update GUIDANCE_H gains for quadrotor example
  [rotorcraft][messages] GUIDANCE_H_INT message
  [nps] don't bypass ahrs by default
  [rotorcraft] use horizontal guidance ref by default
  [supervision] allow launching of external tools with absolute path
  [dfu] print exception
  [spi] remove warning
  [doc][modules] minor update to sonar doc
  [sonar] split sonar modules with and without ins binding
  [sonar] and event hook to use the sonar with the ins
  ...
Merge remote-tracking branch 'paparazzi/stm32f4' into stm32f4