Shapeout2

- build: pin rpy2 to 3.4.2 on Windows (84)

- setup: migrate to pyqtgraph 0.12.0
- setup: bump dclab from 0.33.1 to 0.33.3
- docs: fix rtd build

- setup: remove deprecated setup.py test
- setup: bump dclab to 0.33.1 (filters were ignored when exporting
trace data to hdf5,
see https://github.com/DC-analysis/DCKit/issues/17)

- feat: add background correction in quickview (54)
- fix: workaround for different plot widths due to title label (33)

- build: add pyinstaller hook for pyqtgraph

- fix: preferences dialog did not open in macOS App bundle (76)
- enh: disable R settings in preferences dialog if rpy2 is missing
- build: bump dclab from 0.29.1 to 0.32.4 (this should have happened
in the 2.5.0 release which introduced R-lme4 analysis)
- build: bump pyqtgraph to commit c1900 (post 0.11.1)
which mainly improves plot export (59)
- tests: introduce manual tests that require a human in "tests-manual"
- ref: key [calculation]: "emodulus model" is deprecated in dclab
- ref: use "lut_identifier" instead of deprecated "method" keyword when
retrieving isoelasticity lines