[UPDATE] Improve php doc and update features

[UPDATE] Improve php doc and update features
Improve php doc for @uses tags when attributes are inherited
(modification of WsdlToPhpStruct::getAttributes() behaviour!)
Minor update when generating comment for array comment type by removing
space after comma
Improve SOAPHeader detection and type determination
Inroduce global value dedicated to the WsdlTophpGenerator class to store
global values and unset them at once
Update WsdlTophpGenerator php doc
Add several test cases for SOAPHeader detection