FW landing bug

Mark FILESYSTEM_ERRCOUNT_NOTIFY_LIMIT as an unsigned int

Fix the compilationof mavlink_mission.cpp failing with

error: comparison between signed and unsigned integer expressions
[-Werror=sign-compare]

qurt: updated dspal version

Added declaration of write() call

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

qurt: Updated dspal version

Added missing extern "C" blocks

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

POSIX: Improve shell so it does not spam the user, enable CTRL-C to actually quit the application. Twiddle the app boot delay to avoid a race with the commander app. Needs a proper fix on the startup sequencing.

Navigator: Fix priority to run at much lower priority than controllers, but higher than common stuff.