Merge branch '3406_sftp_error_31'

Merge branch '3406_sftp_error_31'

* 3406_sftp_error_31:
  (panel_operate_init_totals): fix directory size calculation.
  (panel_operate_init_totals): change the 'source' argument type...
  sftpfs: handle file operation errors.
  (sftpfs_close_file): return actual result of sftp file close operation.
  (sftpfs_waitsocket): refactor and use it for file and directory operations.
  Clarify usage of sftpfs_internal_stat() return value.
  sftpfs: refactoring: move initialization of sftp stat operations to separate function.
  sftpfs: refactoring: move initialization of sftp operation to separate function.
  (sftpfs_waitsocket): handle socket errors.
  sftpfs: refactoring: move handling of socket errors to separate function.
  (sftpfs_fstat): use sftpfs_attr_to_stat().
  sftpfs: refactoring: move obtaining of stat info from sftp attributes to separate function.
  sftpfs: refactoring: move error check to separate function.
  Fix sftp error 31 (proto 4 and 2)
  sftp handle LIBSSH2_FX_PERMISSION_DENIED as EACCES.
  Ticket #3406: sftpfs: fix -31 SFTP Protocol Error when transferring file via SFTP Link.