ui: fixed autocompletion issues

* click in autocompletions list causes search
* right arrow for autocompletion
* changed query operator has from '>' to '.' and operator sub from '.' to '+'
* fixed autocompletions to fit to query
and
* fixed spectral layouting endless looping on unconnected node

src/lib/utility/utilityString.cpp

@@ -2,6 +2,7 @@
 
 #include <algorithm>
 #include <cctype>
+#include <iterator>
 #include <string>
 
 namespace utility
@@ -117,6 +118,13 @@ namespace utility
 		return res.first == prefix.end();
 	}
 
+	std::string toLowerCase(const std::string& in)
+	{
+		std::string out;
+		std::transform(in.begin(), in.end(), std::back_inserter(out), tolower);
+		return out;
+	}
+
 	bool equalsCaseInsensitive(const std::string& a, const std::string& b)
 	{
 		if (a.size() == b.size())