WIP: dynamic baro altitude + airspeed

[Stifael]

The file logdynamicpressure contains function for estimating airspeed from tilt angle (from paul priseborough) and functions to prepare data for dynamic barometric altitude change analysis.
The notebook "Log based dynamic barometer altitude" contains a first example of dynamic barometric altitude change estimation.
I added the two files here as a starting point for having a common px4 analysis repository, if that is something that is desired to have in the near future.
ToDo (in case the plan is to use px4tools as the common analysis tool):

• add unit tests
• improve the estimation of the static altitude / pressure instead of just taking the average for each altitude setpoint
• change dynamic altitude estimation to dynamic pressure estimation. this requires to log baro pressure data

[coveralls]

Coverage decreased (-0.5%) to 30.563% when pulling 12c95c1 on Stifael:airspeed_analysis_2 into 83e32e6 on dronecrew:master.

[LorenzMeier]

This is missing an unit test

[coveralls]

Coverage decreased (-0.5%) to 30.563% when pulling b929837 on Stifael:airspeed_analysis_2 into 83e32e6 on dronecrew:master.

[coveralls]

Coverage decreased (-0.5%) to 30.543% when pulling a7e9f23 on Stifael:airspeed_analysis_2 into 83e32e6 on dronecrew:master.