[bp/r50461][SEC] installer: Convert $_GET parameters related to multitiki to $_POST. Please test as I don't have a multiki running to test with.

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/6.x@50555 b456876b-0849-0410-b77d-98878d47e9d5
[bp/r50557][SEC] tiki-print: enhance permission check (thanks luci)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/6.x@50560 b456876b-0849-0410-b77d-98878d47e9d5