add force option

[tobiaskohlbau]

Hi thanks for your project, very useful tool ✌

I've got the issue that when using the new go version in conjunction with force closing the application the socket is left behind. (I have a shortcut to the executable within my taskbar and close the program quit often without issuing ctrl+c in the opened command prompt)

This PR adds an option --force which in case of an AddressAlreadyInUse error tries to unlink the specified socket path. Maybe you consider this option as a viable addition to your project.

[lars18th]

Hi,

Is this project stalled?

[benpye]

Hey, sorry I still use this often.

@tobiaskohlbau if you can split the force option from the other commits I'll try and get this in.

[lars18th]

Hey, sorry I still use this often.

Me too! It's the only solution to use PuTTY Pageant with the Windows 10 native SSH client.

@tobiaskohlbau if you can split the force option from the other commits I'll try and get this in.

I hope this PR will be merged then.

[tobiaskohlbau]

Sorry for the delay, I missed the comments.

@benpye of course not every commit should be part of this PR I forgot that I didn't created a specific branch for this feature and kept working on it. I've cleaned everything up and the PR should be clean by now. Let me know if there are some suggestions or changes you would like to have before merging this.