Development version (aimed for Isinglandr 0.2.0)

Added functions calculate_stability_se() and compare_stability() for calculating the standard error of the stability metrics and comparing the stability metrics between two networks, respectively.
Added the autolayer.stability_2d_Isingland_matrix() method. The structure of the stability_2d_Isingland_matrix objects changes slightly to accommodate the new method. Users may need to re-generate previously stability_2d_Isingland_matrix objects
Bug-fix for make_3d_Isingland():
- The function now allows character values for the x and y arguments.

Isinglandr 0.1.1

Bug-fix for the Shiny app (shiny_Isingland_MDD()):
- Load the data to the Shiny app environment;
- Check if gifski is installed, which is required to render the animations (also added gifski as a suggested package).