Dclab

- Replace OpenCV with imageio
- Add (ancilliary) computation of volume (11)
- Add convenience methods for `Configuration`
- Refactoring (8):
- Separate classes for .tdms, dict-based, and hierarchy datasets
- Introduce "_events" attribute for stored data
- Data columns (including image, trace, contour) are accessed via
keys instead of attributes.
- Make space for new hdf5-based file format
- Introduce ancilliary columns that are computed on-the-fly
(new "_ancilliaries" attribute and "ancilliary_columns.py")

- Add look-up table for elastic modulus (7)
- Add filtering option "remove invalid events" to remove nan/inf
- Support nan and inf in data analysis
- Improve downsampling performance
- Refactor downsampling methods (6)

- Add new histogram-based kernel density estimator (2)
- Refactoring:
- Configuration fully handled by RTDC_DataSet module (5)
- Simplify video export function (4)
- Removed "Plotting" configuration key
- Removed .cfg configuration files

- Support npTDMS 0.9.0
- Add AVI-Export function
- Add lazy submodule for event trace data and rename `RTDC_DataSet.traces`
to `RTDC_DataSet.trace`
- Add "Event index" column

- Compute sensible default configuration parameters for
KDE estimation and contour plotting
- Speed-up handling of contour text files
- Add support for "User Defined" column in tdms files

- Implement hierarchical instantiation of RTDC_DataSet
- Bugfix: Prevent instances of PolygonFilter that have same id
- Load InertiaRatio and InertiaRatioRaw from tdms files