A mimic posing as a statue was displayed as a tengu statue (and
recognizeable as such now that statues are displayed as the corresponding
monster rather than rock-class back tick), but the lookat code described
it as a giant ant statue (since there was no obj->corpsenm available to
indicate the monster type, it defaulted to 0). This adds monst->mextra
field `mcorpsenm' so that mimics have a place to remember what sort of
statue or corpse they are mimicking. And it picks a random monster type
when they take such forms so that the old tengu hack becomes irrelevant.
newmextra() and newoextra() initialized pointers via memset(...,0)
which is not portable; switch to explicit assignments. The wizard mode
code to display memory used for monsters and objects added in amounts
for the miscellaneous things pointed to by monst->mextra and obj->oextra
structs but didn't include memory for those structs themselves; add it.
Simplify monster save/restore slightly; there's no need for extra zeroes
to represent monst->mextra->X sizes when monst->mextra is null.
Update the startup banner for 2009. I should have done this with a
separate patch but I'm taking a shortcut. :-]