Features

New realign functionality.
Support for event-filtering.
Support for subtraction and addition for (realigned) event data.
Non-range slicing changed to preserve coords as attrs rather than dropping
scipp.neutron: Instrument view with advanced geometry support, showing correct pixel shapes.
Instrument view working on doc pages.
Made it simpler to add new dtype and support transform for all types.
Comparison functions such as less, greater_equal, ...
all and any can work over all dimensions as well as explicitly provided dimension argument
It is now possible to convert between Scipp objects and Python dictionaries using to_dict and from_dict.
New functions collapse and slices can be use to split one or more dimensions of a DataArray to a dict of DataArrays.
You can now inspect the global object list of via the repr for scipp showing Datasets, DataArrays and Variables
Internal cleanup and documentation additions.

Noteable bug fixes

Several fixes in the plotting (non-regular bins, colorbar limits, axes tick labels from unaligned coordinates, etc...)

Coord and attributes names for neutron data have been standardized, now using hyphens instead of underscore, except for subscripts. Affected examples: pulse-time (previously pulse_times), source-position (previously source_position), sample-position (previously sample_position), detector-info (previously detector_info).
scipp.neutron.load must use advanced_geometry=True option for loading detector-info and pixel shapes.
Normalization of event data cannot be done directly any more, must use realign.
Plotting variances in 2D has been removed, and the API for using matplotlib axes has been simplified slightly, since we no longer have axes for variances:
- Before: plot(..., mpl_axes={"ax": myax0, "cax": myax1})
- After: plot(..., ax=myax0, cax=myax1)
Plot with keyword argument collapse has been removed in favour of two more generic free functions that return a dict of data arrays that can then directly be passed to the plot function:
- collapse(d, keep='x') slices all dimensions away to keep only 'x', thus always returning 1D slices.
- slices(d, dim='x') slices along dimension 'x', returning slices with ndim-1 dimensions contaiing all dimensions other than 'x'.

Owen Arnold, David Fairbrother, Simon Heybrock, Daniel Nixon, Pawel Ptasznik, Piotr Rozyczko, and Neil Vaytet