Screen buffer

When a client attaches to an existing session, the session command output is not available to him. The problem is not noticeable when the program (top, man, etc.) in the session is able to redraw its output.

But this does not work with non-interactive utilities. The output of commands in bash will not be available to the client connecting to the session.

To solve this, we add a buffer that contains the last few lines of the session output. When a new client attaches, the contents of this buffer are sent to him.

This PR could address #57, #32 and maybe more.

this is brilliant!

any chances of merging @martanne?

@megalithic I haven't seen activity here in years. I maintain my fork.

@megalithic I haven't seen activity here in years. I maintain my fork.

thanks @legionus! i've switched to building from your repo from source. cheers!

thanks @legionus! i've switched to building from your repo from source. cheers!

@megalithic If you have any other suggestions, I'm ready to add to my fork. I hope in the future I will have a chance to discuss them with upstream.