honor run option with a default maze of 30x30

default_args in project
Display.main()
  if argument is empty ignore it
  if file read fails, exit
add a WHEREWHAT file
extract MazeParamEditor to share it, prepare for having a GUI instead of console

java/org/artisanlogiciel/games/MazeParams.java

@@ -3,7 +3,7 @@ package org.artisanlogiciel.games;
 import java.io.File;
 
 /**
- * MazeParams was autogenerated by ./generate_newclass.sh
+ * MazeParams contains parameters for a Maze generation
  **/
 public interface MazeParams
 {