Dclab

- Setup: add dependencies for statsmodels
- Tests: filter known warnings
- fmt_hdf5: import unknown keys such that "dclab-verify-dataset"
can complain about them

- BREAKING CHANGES:
- definitions.feature_names now contains non-scalar
features (inlcuding "image", "contour", "mask", and "trace"). To
test for scalar features, use definitions.scalar_feature_names.
- features bright_* are computed from mask instead of from contour
- Bugfixes:
- write correct event count in exported hdf5 data files
- improve implementation of video file handling in fmt_tdms
- add new non-scalar feature "mask" (48)
- removed configuration key [online_contour]: "bin margin" (47)
- minor improvements for the tdms file format

- Bugfix: CLI "dclab-tdms2rtdc" did not work for single tdms files (45)
- update configuration keys:
- added new keys for [fluorescence]
- added [setup]: "identifier"
- removed [imaging]: "exposure time", "flash current"
- removed [setup]: "temperature", "viscosity"
- renamed feature "ncells" to "nevents"

- ref: do not import missing features as zeros in fmt_tdms
- CLI:
- add tdms-to-rtdc converter "dclab-tdms2rtdc" (36)
- improve "dclab-verify-dataset" user experience
- Bugfixes:
- "limit events" filtering must be integer not boolean (41)
- Support opening tdms files with capitalized "userDef" column names
- OSError when trying to open files from repository root

- CLI: add rudimentary dataset checker "dclab-verify-dataset" (37)
- Add logic to compute parent/root/child event indices of RTDC_Hierarchy
- Hierarchy children now support contour, image, and traces
- Hierarchy children now support and remember manual filters (22)
- Update emodulus look-up table with larger values for deformation
- Implement pixel size correction for emodulus computation
- Allow to add pixelation error to isoelastics (`add_px_err=True`) (28)
- Bugfixes:
- Pixel size not read from tdms-based measurements
- Young's modulus computation wrong due to faulty FEM simulations (39)

- Remove all-zero dummy columns from dict format
- Implement hdf5-based RT-DC data reader (32)
- Implement hdf5-based RT-DC data writer (33)
- Bugfixes:
- Automatically fix inverted box filters
- RTDC_TDMS trace data contained empty arrays when no trace
data was present (trace key should not have been accessible)
- Not possible to get isoelastics for circularity