Merge pull request #964 from PX4/px4io_fixes

Px4io fixes
Merge branch 'master' into offboard2
Merge pull request #965 from PX4/stack_fixes

Stack fixes
Merge branch 'master' of github.com:PX4/Firmware into mtecs
mavlink app: Clean up allocations
Converted streams to new API, saving a bunch of RAM
mavlink app: Fix compile error
mavlink app: Finish porting all messages to new scheme
commander: don't require good EPH for local_position_valid, position_estimator_inav: estimate EPH/EPV and publish it in local position topic
Merge branch 'master' into mc_mixer_fix
ekf_att_pos_estimator: fixed files names and perf counters names
ekf_att_pos_estimator: module.mk fixed
Merge pull request #971 from PX4/ekf_cleanup

akf_att_pos_estimator: cosmetic cleanup
commander: missed 'break' in 'switch' added
Merge branch 'master' into ekf_auto_mag_decl
Merge remote-tracking branch 'upstream/master' into mtecs
Merge remote-tracking branch 'upstream/mtecs' into mtecs
Merge pull request #942 from PX4/mc_mixer_fix

Multirotor mixer: more careful limiting
fw pos control: landing: fix argument order
fw att: robustify main loop against non finite numbers and limit error output rate