wmcliphist: Add version 2.0 to repository.

Obtained from:
http://linux.nawebu.cz/wmcliphist/wmcliphist-latest.tar.gz
wmcliphist: Add X11 build flags; otherwise wmcliphist fails to build.
wmcliphist: Add <sys/stat.h> to includes.

Otherwise, we get the following compiler warning:
history.c:289:2: warning: implicit declaration of function ‘chmod’
[-Wimplicit-function-declaration]
  if ((chmod(fname, S_IRUSR|S_IWUSR)) != 0) {
  ^
wmcliphist: Fix unused but set variable compiler warning.

In particular,
utils.c: In function ‘from_utf8’:
utils.c:13:7: warning: variable ‘error_code’ set but not used
 [-Wunused-but-set-variable]
  gint error_code;
       ^
wmcliphist: Switch from angled brackets to quotes for local includes.
wmcliphist: Remove trailing whitespace.
wmcliphist: Remove foodock library; use GTK dockapp code from wmpasman.
wmcliphist: Replace deprecated GTK symbols.
wmcliphist: Replace xpm icons with png.

In preparation for eventual switch to Cairo/GTK3.
wmcliphist: Migrate to GTK3; remove bitmaps in favor of Cairo for mask.
wmcliphist: Fix new compiler warnings that appeared after GTK3 transition.
wmcliphist: Remove .spec file; not needed upstream.
wmcliphist: Add manpage from Debian.
wmcliphist: Remove Mercurial directory.
wmcliphist: Add -v command line option to print version.
wmcliphist: Add -b command line option to select which clipboard to manage.
wmcliphist: Release version 2.1.
Import upstream version 2.1.
Remove files which have been removed upstream.
debian/compat: Bump to 9.