Add `random_port` function to generate a non-priviliged port number.
Fix typo
Use local port forwarding on '-L' command line option.

Use the `ssh -L` option to forward a random local port to the remote
cups port and execute `lp`/`lpr` locally.
Local port forwarding starts background session
Use (set -x; ...) subshell also for local forwards
Add '-C' option to specify remote cups port.

Furthermore:
 - rename variable `port` => `cupsport`
 . in function `random_port` make variable `port` local
Update documentation for local forwards
Update zsh-autocompletion for local forwards
Add NOTE: concerning multiple forwards
Merge branch 'master' into local-port-forward

Conflicts:
	uniprint
Use correct files variable in local-forward case
Require manual terminate for local-forwards as well
Fix missing LR escape in _uniprint
Fix syntax and semantic errors in local-port-forward code
Merge branch 'local-port-forward'