Double unescape bug in PHP module

[jw35]

There's some suggestion that there's a bug somewhere that results in a double URL-unescape when decoding response messages. This then results in signature validation failures. The suggestion is that this may trigger where data in the response message contains non-ASCII characters.

There is some further information on this is UIS RT ticket #255722, in particular that the URL causing the problem may have been something like

http:///formnew/viewsw.php?id=20608&element_5_3=Möller

[jw35]

Copy of RAVEN093 in master TODO list