Update submodule matrix to latest Tue Dec 10 00:39:17 UTC 2019
Update submodule matrix to latest Tue Dec 10 00:39:17 UTC 2019

    - matrix in PX4/Firmware (478a27ee8843a9bd91a0254f6b01a6a9c01946a4): https://github.com/PX4/Matrix/commit/a8009a36a3668da0cbab0cb028b6997cd8179dc1
    - matrix current upstream: https://github.com/PX4/Matrix/commit/4f3565da94d00c4cd1feb560f1f72a81296522f8
    - Changes: https://github.com/PX4/Matrix/compare/a8009a36a3668da0cbab0cb028b6997cd8179dc1...4f3565da94d00c4cd1feb560f1f72a81296522f8

    4f3565d 2019-12-09 kritz - Add asserts (#115)
2f63981 2019-12-06 kritz - Add several functions that are useful for coavriance matrices: (#114)
5cbcf60 2019-12-05 kritz - Set Matrix's col amd row to single value (#113)
ef442fa 2019-12-05 kritz - Getter function for the diag elements of slice (#112)
de6a2d3 2019-12-04 kritz - Slice assign value (#111)

acfloria/Firmware,PX4/Firmware,PX4/Firmware,acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,krbeverx/Firmware,PX4/Firmware,acfloria/Firmware,acfloria/Firmware,PX4/Firmware,acfloria/Firmware,acfloria/Firmware,krbeverx/Firmware,krbeverx/Firmware,krbeverx/Firmware,PX4/Firmware,PX4/Firmware,PX4/Firmware,krbeverx/Firmware,krbeverx/Firmware