Another quick bug fix release, correcting problems caused by the recent upgrades.

• Exclude category option was broken. Fixed that.
• Searching for a non-existing category ID caused an error. Fixed that.
• Occasional blank screens of death occurred when multibyte string operations weren’t installed. That should not happen anymore.
• Fallback to OR search was a bit broken.
• Premium only: New users are automatically indexed, that didn’t work before.