SFTP: Add touch function
SFTP: Add touch function

Also make it so chmod will auto-switch the filename / permissions if they're not in the "right" order (PHP's chmod and ftp_chmod order them differently from each other so this'll make phpseclib consistent with both)

melya/phpseclib,kenichiii/phpseclib,creatuity/phpseclib,danog/phpseclib,creatuity/phpseclib,melya/phpseclib,thaigialai1987/phpseclib,danog/phpseclib,splitice/phpseclib,kenichiii/phpseclib,ericariyanto/phpseclib,phpseclib/phpseclib-php5,phpseclib/phpseclib-php5,metaclassing/phpseclib,paragonie-scott/phpseclib,paragonie-scott/phpseclib,thaigialai1987/phpseclib,phpseclib/phpseclib,ericariyanto/phpseclib,splitice/phpseclib,metaclassing/phpseclib,terrafrost/phpseclib