ggatessh working tree

This is a working tree for ggate work.

This is a variant of ggatec using sftp instead of talking to ggated.

It uses the libssh2 library with a few modifications. The build system will be updated to compile and use libssh2. There is at least one minor modification needed to turn off read-ahead for sftp support.

By default, libssh2 assumes that you’ll read a whole file sequentially in blocking mode, and if it does not do this, there will be pipeline stalls. In our case, this would result in lots of wasted bandwith as we will be seeking around the file to read and write, and so this feature needs to be disabled.