+ 6.4 (Dec 31, 2022)
+ Interface changes:
+
+ + none
+
+ Added extensions:
+
+ + none
+
+ Added internal functions (other than "_sp" variants):
+
+ + add _nc_free_termtype1 and _nc_free_tparm, for memory-leaks
+
+ Removed internal functions:
+
+ + none
+
+ Modified internal functions:
+
+ + none
+
+ 6.3 (Oct 21, 2021)
+ Interface changes:
+
+ + the definition of TERMTYPE2 is now internal, not visible in the ABI,
+ like the enclosing TERMINAL which was previously made opaque. This
+ was done to provide SCREEN-specific "static" variables in terminfo.
+
+ Added extensions:
+
+ + add sp-funcs for erasewchar, killwchar.
+
+ Added internal functions (other than "_sp" variants):
+
+ + _nc_safe_fopen and _nc_safe_open3 limit privileges if possible when
+ opening a file; otherwise disallow access for updating files.
+
+ + _nc_tiparm is a variant of tiparm which is used when all of the
+ parameters are known to be numbers rather than possibly strings.
+
+ + _nc_reset_tparm improves tic's checks by resetting the terminfo
+ "static variables" before calling functions which may update them.
+
+ Removed internal functions:
+
+ + none
+
+ Modified internal functions:
+
+ + _nc_trace_ttymode passes pointer to const data
+
+ + _nc_tparm_analyze passes pointer to int*, not int[]
+