Add a new debug flag prevent_pline, which prevents all messages
from going out to the UI. This prevents the tests from stopping
for -more-.
Add rudimentary tests for applying whistles, camera, and stethoscope.
Test generation of every object, both via des.object and obj.new.
Expose FIRST_OBJECT and LAST_OBJECT numbers to lua.
Add lua nh.int_to_objname, a function to convert integer value to
object base name and class.
Allow creating new nethack lua object by specifying id and class.
If the core frees the obj struct referred by lua, don't free it,
just mark it as OBJ_LUAFREE - lua will free it in gc once all
the references to it are gone.
