Hi ho

This version has the global variable use removed and a memory leak fixed.

There's still one leak left when I do a simple

   curl scp://user:passwd_at_localhost/~/file

Leak detected: memory still allocated: 59 bytes
At 80b9594, there's 59 bytes.
  allocated by ssh.c:220

... which happens to be the malloc replacement for libssh2, so there's either
a resource libssh2 allocates for us that we don't free, or libssh2 itself
leaks this data.

I take it there's no major objection against me committing this to give us a
better common floor to continue working from?