ncurses 6.1 - patch 20180127

ncurses 6.1 - patch 20180127

+ updated release notes
+ amend a warning message from tic which should have flagged misuse
  of "XT" capability in "screen" terminal description.
> terminfo changes:
+ trim "XT" from screen entry, add comments to explain why it was
  not suitable -TD
+ modify iterm to use xterm+sl-twm building block -TD
+ mark konsole-420pc, konsole-vt100, konsole-xf3x obsolete reflecting
  konsole's removal in 2008 -TD
+ expanded the history section of konsole to explain its flawed
  imitation of xterm's keyboard -TD
+ use xterm+x11mouse in screen.* entries because screen does not yet
  support xterm's 1006 mode -TD
+ add nsterm-build400 for macOS 10.13 -TD
+ add ansi+idc1, use that in ansi+idc adding dch for consistency -TD
+ update vte to vte-2017 -TD
+ add ecma+strikeout to vte-2017 -TD
+ add iterm2-direct -TD
+ updated teraterm, added teraterm-256color -TD
+ add mlterm-direct -TD
+ add descriptions for ANSI building-blocks -TD