Set correct object level for statue contents

Yet another NitroHack Global Level Pointer Bug.  This one caused crashes
when trying to use an object's olev field for anything during special
level creation since it was being set to null.

This is meant to go with commit 1187aabd31 (don't refer to u.uz during
level creation).
(cherry picked from commit 56d2eefb525a517cd047a3569963a0cc17477d90)
Only try to move timers/lights if object has them

This is a minor optimisation that prevents repeatedly looping through
the level timers and lights lists for the majority of objects that don't
have either.

This is meant to go with commit 90f16c9c59 (move lights/timers with
objects that change levels).
(cherry picked from commit 483d138fa690e4e7bc27a2208a49e931507a5d75)
Update commment in transfer_lights()

This is meant to go with commit 90f16c9c59 (move lights/timers with
objects that change levels).
(cherry picked from commit ae46d3e6c6c720201308721a95dfcde1b16c5684)
Clean up timer debugging code
(cherry picked from commit f02f3e9620eddde4caed6799b9e842a827e5873f)
Bump patchlevel to 0.5.5

This release fixes a NitroHack bug with statue contents that interacted
badly with 0.5.4's timer/light source fix causing the game to crash when
entering a level with such statues.
(cherry picked from commit 7557457782d7f981f8b1fe50c39bf6e1e0fdef97)