velocity macros "parameters by reference" no more available

XWiki version 3 has switched to velocity 1.7.
This has garbaged the feature of redefining the value of a macro parameter (a doubtful feature indeed, but one that was used in Curriki).

We need to find all places where this was used and fix them using the setVariable macro.

See explanations here: http://www.xwiki.org/xwiki/bin/ReleaseNotes/ReleaseNotesXWikiEnterprise30#HTheVelocityenginewasupdatedtoversion1.7