Merge branch 'topic/termcap.2'

Merge branch 'topic/termcap.2'

* topic/termcap.2:
  Add WANT_KEY_BINDINGS..
  Support queries of ANY (string) capability
  Add terminfo(5) support (via WANT_TERMCAP_PREFER_TERMINFO)..
  termcap.c: rewrite to implement lazy queries etc.
  Differentiate in between termcap(5) commands and queries
  MLE: add "mle-position" and "mle-prompt" colour mappings
  Turn NCL into M(ailx) L(ine) E(ditor)..
  Add field_detect_width(), visual width of string
  Deduce colours via *termcap* instead!; support all/*..
  nail.1: use -v option to cat(1) if available (Thomas Dickey)
  Rewrite for a generic termcap(5) interface..
  nail.1: "Command line editor" .. "On terminal control and line editor"..
  Many: rename NCL (Nail-Command-Line) to MLE (Mailx-Line-Editor)
  mk-conf.sh: if "feat_yes NCL", look for _PC_MAX_INPUT
  mk-conf.sh: test for fpathconf(2) when going pathconf(2)
  make.rc: enable WANT_TERMCAP by default
  Implement *term-ca-mode* for real..
  Create foundation to turn *term-ca-mode* into something good..
  Drop WANT_EDITLINE support..