ncurses 6.0 - patch 20160116

ncurses 6.0 - patch 20160116

+ tidy up comments about hardcoded 256color palette (report by
  Leonardo Brondani Schenkel) -TD
+ add putty-noapp entry, and amend putty entry to use application mode
  for better consistency with xterm (report by Leonardo Brondani
  Schenkel) -TD
+ modify _nc_viscbuf2() and _tracecchar_t2() to trace wide-characters
  as a whole rather than their multibyte equivalents.
+ minor fix in wadd_wchnstr() to ensure that each cell has nonzero
  width.
+ move PUTC_INIT calls next to wcrtomb calls, to avoid carry-over of
  error status when processing Unicode values which are not mapped.