Bug#1065390: xkeystone: depedency on nickle not available

[Adam Majer]

Package: x11-xserver-utils
Version: 7.7+10

There seems to be a dependency missing, or at least a recommends if a 
strict dependency would pull in too many things

$ xkeystone
/usr/bin/env: ‘nickle’: No such file or directory

$ head /usr/bin/xkeystone
#!/usr/bin/env nickle

To make this utility work, had to install

  cairo-5c, nickle