Made some space for FDs - needs proper fix, but will give hackers some relief
updated mavlink submodule
Merge pull request #1403 from PX4/sdlog2_relief

Made some space for FDs - needs proper fix, but serves well as short-term solution
Merge branch 'master' of https://github.com/PX4/Firmware into VTOL_pull_request, because master has a temporary fix for the lack of file descriptors