[Fix] http protocol options seekable=0 now finally works.
Merge pull request #2644 from ulion/fix_seekable_protocol_option

[Fix] http protocol options seekable=0 now finally works.
GUIFadeLabelControl: fix control being marked as dirty when label stays empty

If used infolabel will return empty string on first use, m_shortText will never be evaluated. If m_shortText is set to false control is marked as dirty so if used infolabel is empty control will be wrongly marked as dirty.