* [abi] Add timestamp to AGL and BARO_ABS
* [make] Add support for c++0x for all architectures
* [math] Add air density calculation
* [gps] Add horizontal and vertical position accuracy
* [boards] PX4FMU change default baudrate and add SBUS
* [ins] Add EKF2
* [tests] Add Bebop2 with EKF2
* [nps] Fix jsbsim simulator initialisation and GPS accuracy
-ggdb3 make slightly bigger .elf files, but allows gdb to understand
macros, which paparazzi uses somewhat extensively.
Make this the default, since it only impacts the size of the debug sections and
not the size of the flashed binary (in the lpc21/stm32 case).
On the linux system we really don't care about these few more bytes...
Since using SIGALRM to call the sys_tick_handler (via setitimer) can cause problems like interrupting some other syscalls
(i.e. read,write, ioctl), setup a separate thread and use timer_fd instead.
That is a Linux-specific set of functions that presents POSIX timers as file descriptors rather than signals.
If the thread runs with a normal priority it can happen that some timer events are missed (and hence sys_time not updated in time).
So added a function to set a higher prio for that thread (needs root rights or properly set up limits for the user).
In some simple tests no events were missed when running with prio 29 via SCHED_FIFO, even if events would be missed,
the sys_tick_handler is called the appropriate number of times (so that the time is correct again after)...
After these changes also fix some bugs discovered in the ardrone navdata reading.
Reading is now done in a separate thread which waits on a condition variable until the navdata_update event loop has copied the buffer.
Freek van Tienen
Felix Ruess
Gautier Hattenberger