Futile ncurses warning

[ablaette]

Across systems, the configure script issues the following warning on the non-availability of ncurses.

• using pkg-config to check whether ncurses is available ... no
  ----------------------- CONFIGURATION CRITICAL --------------------------
  Configuration may fail because 'ncurses' was not found. Try installing:
• deb: libncurses5-dev libncursesw5-dev (Debian, Ubuntu, etc)
• yum: ncurses-devel (Fedora, CentOS, etc)
• csw: libncurses_dev (Solaris)

---

Yet installation works. Check whether ncurses is really necessary any more and drop this warning if not.

[ablaette]

The ncurses library is a dependency of the editline library included in the CWB, but editline is not built for the purposes of this package. So the check for the availability of ncurses is omitted now, and the editline directory is excluded from being included in the package tarball using .Rbuildignore, reducing the size of the tarball somewhat.