LiquidDiffract v1.1.9

Major Changes

• Background refinement
  The background scaling factor (b) can now be refined alongside the density in the Refinement Tab
  Background refinement is optional and can be done independently from or simultaneously with density refinement.
  The background scaling factor set in the Background Subtraction Tab is used as the initial estimate by the solver.
  The figure of merit is redefined to take into account the background scaling - Χ^2(ρ;b)

• LiquidDIffraction publication
  There is now a paper describing LiquidDiffract:
  Heinen, B. J., & Drewitt, J. W. (2022). LiquidDiffract: Software for liquid total scattering analysis. Physics and Chemistry of Minerals, 49:9. doi:10.1007/s00269-022-01186-6
  Please cite this paper if you use LiquidDiffraction in your work!

Minor Changes

• LiquidDiffract.core.core now uses a separate objective function for density and/or background refinement - core.refinement_objfun.
  As a result, the arguments taken by core.calc_impr_interference_function have been redefined. The docs and example scripts have been updated to reflect this.
• Fixed some documentation issues and removed some dead code