Removed $wgSamlConfirmMail; always confirm mail

SAML users with unconfirmed addresses will require a password to
confirm their address, which they don’t have. The $wgSamlConfirmMail
variable is therefore useless.
Error message when required a attribute is missing
Removed comments associated with old variables
Minor layout fixes
Clarified MediaWiki requirements
Removed "th"
Grammar
Clarified MediaWiki vs. SAML users and passwords
Improved error reporting
Merge branch 'master' into email
Fixed code errors
Return control to MediaWiki session system after SSP
Fixed typo
Moved session setup to a place where it works
Added support for MediaWiki < 1.18
Removed preload function

No session hacks must be necessary for this extension to run.
Fixed wrong function call
Override MediaWiki session name with standard PHP name

SimpleSamlPhp uses PHP `session.name` setting for it’s internal
sessions, even when you try to override it with the SSP
`session.cookie.name` setting. In order to let SSP find back the
session it made earlier, MediaWiki should load the session with the
same name that SSP used earlier.

This solution is not perfect; there can be conflicts between SSP and
MediaWiki variables, but it will have to do. Unless there is a better
way to handle this in SimpleSamlPhp.
Removed unnecessary code

This code was believed to be necessary for handling sessions, but turns
out to be unnecessary.
Cleaned global declaration