ncurses 6.0 - patch 20170819

ncurses 6.0 - patch 20170819

+ update "iterm" entry -TD
+ add "iterm2" entry (report by Leonardo Brondani Schenkel) -TD
+ regenerate llib-* files.
+ regenerate HTML manpages.
+ improve picsmap test-program:
  + reduce memory used for tsearch
  + add report in log file showing cumulative color coverage.
+ add -x option to clear/tput to make the E3 extension optional
  (cf: 20130622).
+ add options -T and -V to clear command for compatibility with tput.
+ add usage message to clear command (Debian #371855).
+ improve usage messages for tset and tput.
+ minor fixes to "RDGB" extension and reset_color_pairs().