Create new branch. Goals: Make rocks size patches and frequency configruable. Optional but highly desired: Make rocks denser/more frequent the higher the altitude (make that an optional bool?)

Also the number display is screwed in the settings gui. Same problem as my other patch. Need to compare it to what I did for the other var I did recently (tiles width around rivers to make desert go away) and fix this. This will do to start with.

src/clear_cmd.cpp

@@ -365,7 +365,7 @@ void GenerateClearTile()
 
 		IncreaseGeneratingWorldProgress(GWP_ROUGH_ROCKY);
 		if (IsTileType(tile, MP_CLEAR) && !IsClearGround(tile, CLEAR_DESERT)) {
-			uint j = GB(r, 16, 4) + 5;
+			uint j = GB(r, 16, 4) + _settings_game.game_creation.amount_of_rocks;
 			for (;;) {
 				TileIndex tile_new;