cameo: allow comma between parameters of "drill" (makes use in scripts easier)

- lang.y: allow an optional comma between the parameters of "drill"
- README: explain the new syntax of "drill"

cameo/README

@@ -158,6 +158,7 @@ removed up to the corner point.
 Drill/mill conversion:
 
   drill <min-diameter> <max-diameter>
+  drill <min-diameter>,<max-diameter>
   mill <diameter> <step>
   remainder
   empty
@@ -168,6 +169,10 @@ or "mill", only the toolpaths for this tool remain. The paths that
 have been converted are removed and the paths for which the tool is
 unsuitable are moved to a separate list, the remainder list.
 
+The two parameters of "drill" can be separated by whitespace or by a
+comma. The latter form can be convenient when passing the diameter
+range around in shell scripts.
+
 "remainder" clears the list of paths and sets the list of paths to
 the remainder list. Note that "clear" does not affect the remainder
 list.

cameo/lang.y

@@ -310,7 +310,7 @@ command:
 			gnuplot_append($2, paths);
 			translate(paths, 0, 0, -zo);
 		}
-	| TOK_DRILL dimen dimen
+	| TOK_DRILL dimen opt_comma dimen
 		{
 			struct path **walk;
 
@@ -319,7 +319,7 @@ command:
 			walk = &remain;
 			while (*walk)
 				walk =
-				    classify(walk, try_drill(*walk, $2, $3));
+				    classify(walk, try_drill(*walk, $2, $4));
 		}
 	| TOK_MILL dimen dimen
 		{
@@ -433,3 +433,7 @@ offset_option:
 			$$ = OO_INSIDE;
 		}
 	;
+
+opt_comma:
+	| ','
+	;