Add option to pipe code to an external process

[rpls]

This adds a command line flag --command for the send{,-many} commands that allows a user to specify a shell command to which the code-word is piped. This could, for example, enable a user to pipe the command to xclip to achieve #123. This is more versatile as this would allow a user to script some things, and probably a lot simpler than supporting clipboards in general.

It's just a crude first try, I'm not a rust programmer. But it works for me.

[rpls]

Some questions:

• Should the command line flag be renamed?
• Should this use an asynchronous version of std::process (adds external dependency async-process)?

[piegamesde]

Thank you for the PR. It's a worth while feature to have right now, but be aware that clipboard support might make it obsolete one day.

---

Should the command line flag be renamed?

Yes, see my review comment.

Should this use an asynchronous version of std::process (adds external dependency async-process)?

To be honest, not sure. I think we can always change it to async if the need ever comes up.

[piegamesde]

I just got an idea for a different approach to the problem that I'd like to discuss: how about having a command that generates a code? Example usage:

code=$(wormhole generate-code)
wormhole send --code=$code
wormhole recieve $code

code=$(wormhole generate-code)
xclip $code
wormhole send --code=$code

[piegamesde]

Since when do we have a code coverage bot?! :D

[rpls]

I just got an idea for a different approach to the problem that I'd like to discuss: how about having a command that generates a code? Example usage:

code=$(wormhole generate-code)
wormhole send --code=$code
wormhole recieve $code

code=$(wormhole generate-code)
xclip $code
wormhole send --code=$code

That would work too I guess. And users could probably have a shell alias or function in their profile to have this in one go.

[rpls]

I worked in all the suggestions, but the windows support is untested.

[zeri42]

generate-code)
wormhole send --code=$code
wormhole recieve $code

if you do that you can use anything as a code that starts with a number like this:

code=$((RANDOM%1024))-$(head -c 16 /dev/urandom | xxd -ps)
xclip $code
wormhole send --code=$code

[piegamesde]

I just made #141. Please give it a try. Do we still need your proposed solution for some use cases? Are those use cases worth supporting?