Display transfer progress
Closes #3
Borrowed some files from OpenSSH:
atomicio.* misc.* progressmeter.* taken from http://openbsd.cs.toronto.edu/cgi-bin/cvsweb/src/usr.bin/ssh/
misc.* modified to throw away OpenSSH specific stuff
Also borrowed strlcat.c from libc (http://openbsd.cs.toronto.edu/cgi-bin/cvsweb/src/lib/libc/string/)
The reason for borrowing is because some UNIX systems do not have GNU libc out-of-box