SFTP classes

We need SFTP capabilities https://api.libssh.org/stable/libssh_tutor_sftp.html

This is what I'm thinking

SFTPSession  
   mkdir : bool  
   rmdir : bool  
   openFile(string, access_type) : SFTPFile  
   openDir(string) : SFTPDir
   error() : string  
   canonicalize (string) : string  
SFTPFile  
   write(string) : size_t  
   read(size_t) : string  
   close() : bool  
   seek() : size_t  
   tell() : size_t  
SFTPDir  
   hasNext() : bool <-- sftp_dir_eof(dir)  
   next() : struct imitating sftp_attributes_struct with c++ types.