More organic cave automata

Happy New Year!&#xA;There is a well-known cellular-automaton based method for generating images that look like caves.&#xA;Each cell is either &ldquo;empty&rdquo; or a &ldquo;wall&rdquo;. The rule is: if the immediate 9x9 grid centered on a cell has 5 or more walls, that cell should be a wall in the next step. Otherwise, it should be empty.&#xA;If you initialize the grid randomly with some density,…