windows-tty: Use nhraykey by default if the players keyboard layout is
non-english as reported in H4216
windows-tty: We now support changing altkeyhandler in game
+windows-tty: augment codepage850-to-Unicode mappings that are not displayable
+ with codepage437-to-Unicode mappings that are, to help ensure
+ that rogue-level characters in the status line match their appearance
+ on the map
windows: Added ntassert() mechanism for Windows based port use
windows: heed OPTIONS=symset:default in config file if it is present
tty: significant optimizations for performance and per field rendering