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.