v0.8.0-alpha FENTON SAURUS

• More unit tests
• colour connector "swatch" generator script
• started work on dark/flat field generator
• Datum archives - a file format (.PARC) for saving Datum objects, with an associated
  input method and exporters. Required because we have no other way of saving images
  with uncertainty and DQ.
• DatumStore class wraps Archive objects so we can store Datum (this is used for the datum archives)
• expr uses a DataWidget, as does TabData.
• 1D vectors supported as a Datum.NUMBER type. Modifications made to datumfuncs
  and operators permit this. Notably, the semantics of mean, sd, sum, min and
• square bracket parsing in expressions generates vector-creation and vector-index instructions
  max have changed to operate band-wise and generate a vector when performed on images.
• Multiband extraction, e.g. a$[640,550,440].
• .bands property generates a vector of wavelengths, so we can do a$b.bands, to get
  the bands in a that are also in b, in the same order as in b.
• .u property
• properties graph tests and QoL work for test building
• precedence adjustments in expressions
• getSelection in document can help get selected nodes in plugins
• serialiseFields does a deepcopy - fixes undo bugs
• fixes to roiexpr; it no longer keeps UI data in the node so undo works better
• Cookbook in progress, but not part of the main repository to allow it to be updated more frequently
• First release for Zenodo