Small improvements

Various improvements to texts.
Added two more hints to the maze.
Reduced double click delay.
Autosave is now enabled by default.
Fixed using None as a dict key. (really this time)
Fixed displaying nested lists.
Fixed some issues caused by vertical tabs.
Fixed the %= operator.
Fixed get_cost returning an empty list instead of an empty dict when called on some entities.
Fixed "This is not a valid statement" error message at the beginning of the file when there is a random comma somewhere.
Fixed undo not causing the game to reparse the code.