added a 'yscale' value to replace 'ysort': how oblique the view of the game is can now be tweaked, and objects are automatically not sorted by y-value if the view does not have an oblique angle
improved 'log.write': it now works much like lua's print in that it can take variable argument lists. It can also be drawn anywhere
queries check whether objects are purged: purged object should never be considered by any checks, they should just be ignored and, eventually, removed