[FIX] slides: Fix URL with illegal colon in from being interpreted as a protocol by ensuring it is relative (thanks luciash)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/11.x@46526 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] slides: Fix page names with spaces, accents etc in (thanks marclaporte)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/11.x@46527 b456876b-0849-0410-b77d-98878d47e9d5