simlandr 0.3.0

• Further improved documentation, function, and class names, and cleaned unnecessary exported functions. Removed some deprecated functions.
• Made the parameter names of the landscape functions more consistent; used better default values for landscape functions.
• For single simulation landscape functions, added make_*d_single() alias.
• Removed some default values for barrier calculation functions (they are often not suitable and can be misleading).
• Added print(), summary() and plot() methods for several classes.
• Replaced get_geom() with a method of the autolayer() generic function from ggplot2. get_geom() is now deprecated.
• Replaced get_barrier_height() with a method of the summary() generic function. get_barrier_height() is now deprecated.
• Renamed hash_big.matrix class to hash_big_matrix for consistent use of dots; renamed related functions accordingly.
• Added coda::cumuplot() as a possible option for check_conv().
• For barrier_batch objects, renamed the column b to barrier to avoid possible conflicts.
• Removed some unnecessary messages.
• Added some examples to README.
• Updated the vignette: updated some function, object, and parameter names; removed some references that we are now questioning.
• Bug fix: Parameter vg in make_barrier_grid_2d() and make_barrier_grid_3d() was changed to ag and the class of this parameter was changed from var_grid (deprecated) to arg_grid.