IThread.Change function

Update a thread in the database
If $id = 0 the currently loaded thread will be changed and updated in the database,
else currently loaded thread won't be changed and data will be written to another thread in the database.
$User and $UserName are only updated if $User != -1.
$Options is only updated if it's != -1.

function IThread.Change ($id, $Forum, $User, $UserName, $Subject, $Options = -1);