ability to send several files at the same time. We need to accept them all before transfer starts for the moment.

Name of filetransfer content is now random to be able to have 2 transfer in the same session. send and handle content-add in filetranfer

 - Don't use XTLS when using proxies

wrap IO operations on SSL.Connection objects in try, catch SSL exceptions caused by SSL rehandshake request and simply ignore, retrying the IO should succeed.

TODO: manually handle handshake states to allow non-blocking I/O

Also use sed to remove now unneeded Vim lines, 2to3 -f ws_comma to fix
some whitespace, and fix some other madness manually.