xjed package should provide jed via alternatives

[G. Milde]

Dear fellow packagers,

xjed can be started without X via a simple wrapper script like::

  #!/bin/sh
  unset DISPLAY
  exec xjed $*

I have it here as `/usr/local/bin/jed`, however IMO, the xjed package
should provide the `jed` command via the alternatives system.

Idea: 

Package xjed should:

 * save the above wrapper as `xjed-without-x` on a sensible place.
 * register it as /usr/bin/jed  with alternatives

Package jed should:

 * save the jed executable under a different name
 * register it as /usr/bin/jed with a higher priority than xjed-without-x 


Günter