spatialwarnings v2.0.0

This is a major release of spatialwarnings, with the following changes:

Improvements:

• New methods are available to produce null matrices, on top of shuffling the
  original matrix (e.g. based on smoothing the original matrix).

• Significance of Power-law range can now be tested using indictest().
  Using plot_distr() on the resulting objects will display the 0.05/0.95
  quantiles of the null patch size distributions.

• The package gains a generic function display_matrix, to eyeball the
  matrices being used in spatialwarnings objects using ggplot2

• Improved the fitting of distributions, which should be more robust now.

• Speed improvements in label()

Bug fixes:

• Fixed a bug where the normalization constant for truncated power-laws was
  miscalculated

Removals:

• All the deprecated *_spews functions are now defunct (removed).

• Most indicator_* functions are now deprecated.

Misc changes:

• Lots of duplicated code has been removed

• Minor changes in print/summary methods

• The FAQ has been expanded and improved. See the following page:
  https://alex.lecairn.org/spatialwarnings-faq.html

• Dependency to VGAM is now removed