Added recovery token autodetect

Recovery token (or identity token) is a hash so its length is 32 byte or
more (depending on encoding e.g. MD5 or SHA256 + hex encode or URL
encode)
This update automatically detects and uses a provided recovery token if
it's a hash, or computes it using
md5(strrev($identity));
if it's a MAC address or IMEI code.
Changed NodeString data output

Changed from raw to data length
Added option to return raw icon data

Also unlinks the original image before saving to ensure it's overwritten
Added SetGroupPicture

Fixed thumbnail generation (Whoops again!)
Added SendSetPrivacyBlockedList

Also added prefix to msgId()
Fixed SendGetPrivacyList

Derp.
That's what you get for coding past midnight...
Merge remote-tracking branch 'upstream/master'