Merge pull request #84 from desearcher/master

Added URI handling on newly spawned windows
Moved handler-add and handler-remove after hardcopy.

Else the already defined shortcut :ha calls :handler-add instead of :hardcopy
Updated manpage to include handler documentation
Use custom protocol handler for every opened URI (#82).
Updated manual page for change handler processing (#82).
Added completion for :handler-remove command (#82).
Added completion for :shortcut-remove.

Simplified some of the completions to avoid duplicate code.