Shapeout2

- fix: update Quick View plot when values for the Young's modulus
computation are changed (44)
- fix: use fixed point size in Block Matrix
- enh: improve plot matrix column/row visualization and show flow
rate (45)
- docs: update visualization of Young's modulus look-up tables
using new figure script from dclab
- build: bump Python to 3.8 for Windows builds
- setup: bump dclab from 0.27.5 to 0.27.11 (improvement of hierarchy
child handling)

- fix: correct box filter ranges when feature contains inf values
- enh: add pretty tool icons from KDE breeze theme

- fix: zero-division error when setting "one plot per dataset"
for an empty plot (41)
- build: pin PyQt5 to 5.14.2 on Linux/macOS

- setup: bump dclab from 0.26.2 to 0.27.5 (support for machine
learning features)
- fix: modify the GUI to enable box filtering for ml_score_???
features
- ref: pipeline.get_features now only returns features that are
available (previously all features were returned when no
datasets were in the pipeline)

- fix: export file names were allowed to have invalid characters
- fix: Quick View showed filtered events that were not plotted
(statistics were computed correctly though)
- fix: Quick View was not very informative when all events were
filtered away - a message is now shown
- setup: bump dclab from 0.26.1 to 0.26.2 (fix bin num computation
using Doane's formula)

- fix: marker hue feature data min/max was always computed even if
not selected; for datasets without bright_avg (standard hue) this
resulted in long waiting times
- fix: avoid pyqtgraph error messages in pipeline plots by disabling
hovering events (not used anyway)
- fix: plot export did not work for single plots
- fix: exported event images sometimes had wrong contrast