Implement configuration setting to change the default border of windows

include/client.h

@@ -85,6 +85,14 @@ bool client_is_floating(Client *client);
  */
 void client_change_border(xcb_connection_t *conn, Client *client, char border_type);
 
+/**
+ * Change the border type for the given client to normal (n), 1px border (p) or
+ * completely borderless (b) without actually re-rendering the layout. Useful
+ * for calling it when initializing a new client.
+ *
+ */
+bool client_init_border(xcb_connection_t *conn, Client *client, char border_type);
+
 /**
  * Unmap the client, correctly setting any state which is needed.
  *

include/config.h

@@ -76,6 +76,8 @@ struct Config {
         int container_stack_limit;
         int container_stack_limit_value;
 
+        const char *default_border;
+
         /** The modifier which needs to be pressed in combination with your mouse
          * buttons to do things with floating windows (move, resize) */
         uint32_t floating_modifier;