Search engine: properly interact with filtering

See https://github.com/arybczak/ncmpcpp/issues/260

NEWS

@@ -2,6 +2,7 @@ ncmpcpp-0.8.2 (????-??-??)
 * Help screen: fixed display of EoF keycode
 * Fixed possible integer overflow when resizing screen
 * Fixed fetching lyrics from lyricsmania.com, metrolyrics.com and sing365.com
+* Search engine now properly interacts with filtering
 
 ncmpcpp-0.8.1 (2017-10-11)
 * Setting 'colors_enabled' to 'no' no longer results in a crash.

src/screens/search_engine.cpp

@@ -243,6 +243,7 @@ void SearchEngine::mouseButtonPressed(MEVENT me)
 
 bool SearchEngine::allowsSearching()
 {
+	ScopedUnfilteredMenu<SEItem> sunfilter(ReapplyFilter::Yes, w);
 	return w.rbegin()->value().isSong();
 }
 
@@ -425,6 +426,7 @@ void SearchEngine::reset()
 {
 	for (size_t i = 0; i < ConstraintsNumber; ++i)
 		itsConstraints[i].clear();
+	w.clearFilter();
 	w.reset();
 	Prepare();
 	Statusbar::print("Search state reset");