cameo: added KiCad Gerber input and path merging

- Makefile (OBJS): added gerber.o
- cameo.c (usage, main): new option -g to process input a KiCad Gerber
- gerber.h, gerber.c (gerber_read): parse Gerber files as generated by KiCad
- path.h, path.c (path_reverse_inplace, points_eq, attr_eq, path_connect):
  merge sets of paths with equal endpoints into single paths

cameo/gerber.h

@@ -0,0 +1,22 @@
+/*
+ * gerber.h - Gerber file input
+ *
+ * Written 2010 by Werner Almesberger
+ * Copyright 2010 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef GERBER_H
+#define GERBER_H
+
+#include "path.h"
+
+
+struct path *gerber_read(const char *name, double r_tool_default);
+
+#endif /* !GERBER_H */
+