Fix StringUtils.
Fix StringUtils.

npos should not be used to check if std::string::find* failed.
The doc states that a position greater than or equal to string length is return.

Also cleanup a bit with some autos.

AGGA-IRIT/Radium-Engine,AGGA-IRIT/Radium-Engine,Zouch/Radium-Engine,Zouch/Radium-Engine