photograph experience gains often counted only prior to first move

More details in https://github.com/NetHack/NetHack/issues/1430

track photographed monsters using a distinct bit

also adds a pair of new context fields to track the total number of monsters seen up close,
and the total number of monsters photographed.

So, if somebody wants to add unique end-of-game disclosure statements for tourists that relate to
those, the groundwork should be there.

NOTE: This increments EDITLEVEL, so existing save and bones files will become outdated.

Fixes #1430

include/hack.h

@@ -670,6 +670,7 @@ struct mvitals {
     uchar died;
     uchar mvflags;
     Bitfield(seen_close, 1);
+    Bitfield(photographed, 1);
 };