refactor ecl ekf analysis (#11412)

* refactor ekf analysis part 1: move plotting to functions

* add plot_check_flags plot function

* put plots in seperate file

* use object-oriented programming for plotting

* move functions for post processing and pdf report creation to new files

* add in_air_detector and description as a csv file

* refactor metrics and checks into separate functions

* refactor metrics into seperate file, seperate plotting

* ecl-ekf tools: re-structure folder and move results table generation

* ecl-ekf-tool: fix imports and test_results_table

* ecl-ekf tools: bugfix output observer tracking error plot

* ecl-ekf-tools: update batch processing to new api, fix exception handling

* ecl-ekf-tools: use correct in_air_detector

* ecl-ekf-tools: rename csv file containing the bare test results table

* ecl-tools: refactor for improving readability

* ecl-ekf tools: small plotting bugfixes

* ecl-ekf tools: small bugfixes in_air time, on_ground_trans, filenames

* ecl-ekf-tools: fix amber metric bug

* ecl-ekf-tools: remove custom function in inairdetector

* ecl-ekf-tools: remove import of pandas

* ecl-ekf-tools: add python interpreter to the script start

* ecl-ekf-tools pdf_report: fix python interpreter line

* px4-dev-ros-kinetic: update container tag to 2019-02-13

* ecl-ekf-tools python interpreter line: call python3 bin directly

* ecl-ekf-tools: change airtime from namedtuple to class for python 3.5

* ecl-ekf-tools: update docker image px4-dev-ros-kinetic

* ecl-ekf-tools: fix memory leak by correctly closing matplotlib figures