ncurses 6.0 - patch 20170128

ncurses 6.0 - patch 20170128

+ minor comment-fixes to help automate links to bug-urls -TD
+ add dvtm, dvtm-256color -TD
+ add settings corresponding to xterm-keys option to tmux entry to
  reflect upcoming change to make that option "on" by default
  (patch by Nicholas Marriott).
+ uncancel Ms in tmux entry (Harry Gindi, Nicholas Marriott).
+ add dumb-emacs-ansi -TD
+ improve discussion of early history of tput program.