partial fix for repeated algorithm registration (patch #2101 by Stephan Reuter)

modules/core/src/algorithm.cpp

@@ -321,6 +321,7 @@ AlgorithmInfo::AlgorithmInfo(const string& _name, Algorithm::Constructor create)
 {
     data = new AlgorithmInfoData;
     data->_name = _name;
+    if (!alglist().find(_name, create))
         alglist().add(_name, create);
 }