cameo: documented "area"; miscellaneous cleanup

Also removed the tool diameter argument. We use the diameter from the
path, like "offset" does. In the long run, this convention probably
doesn't make sense, though.

cameo/README

@@ -155,6 +155,22 @@ changes this to cutting a "dogbone" hole such that material is also
 removed up to the corner point.
 
 
+Area clearing:
+
+  area <overlap>
+
+Generate toolpaths to mill (remove) the area enclosed by the current
+path. If there are multiple paths, the area in the outermost is removed
+but the areas covered by enclosed paths are left intact. If they contain
+paths of their own, these are milled again, and so on.
+
+"area" also mills along the outlines of the paths which is similar to
+what "offset" does.
+
+The overlap is the distance by which the areas cleared by parallel paths
+should overlap.
+
+
 Drill/mill conversion:
 
   drill <min-diameter> <max-diameter>

cameo/area.c

@@ -313,12 +313,12 @@ static void fill_path(const struct path *paths, const struct path *path,
 }
 
 
-struct path *area(const struct path *path, double r_tool, double overlap)
+struct path *area(const struct path *path, double overlap)
 {
 	struct path *res = NULL;
 
 	if (!path)
 		return NULL;
-	fill_path(path, path_find_leftmost(path), r_tool, overlap, &res);
+	fill_path(path, path_find_leftmost(path), path->r_tool, overlap, &res);
 	return res;
 }

cameo/area.h

@@ -18,6 +18,6 @@
 #include "path.h"
 
 
-struct path *area(const struct path *path, double r_tool, double overlap);
+struct path *area(const struct path *path, double overlap);
 
 #endif /* !AREA_H */

cameo/lang.y

@@ -328,11 +328,11 @@ command:
 				walk =
 				    classify(walk, try_drill(*walk, $2, $4));
 		}
-	| TOK_AREA dimen opt_comma dimen
+	| TOK_AREA dimen
 		{
 			struct path *tmp;
 
-			tmp = area(paths, $2/2, $4);
+			tmp = area(paths, $2);
 			clear_paths();
 			paths = tmp;
 		}

cameo/test/doit

@@ -1,6 +1,6 @@
 #!/bin/sh
 ../cameo <<EOF
 gnuplot 3 in.gp
-area 3 0
+area 0.13
 write out.gp
 EOF