[LMP] Added IFilterPlugin.
[LMP HS] Implement IPlugin2 and IFilterPlugin.
[LMP] Moved gstutil to util.
[LMP] Moved HTTP streaming stuff to HttStream subplugin.
[LMP] Moved FilterSettingsManager to LMP util.
[LMP] Don't update headers after each registration.
[Util] Added xsd/util.h with OpenXSD().
[LMP] Migrate to Util::OpenXSD().