remove at(index) reference function

remove chrUpr and chrLwr from PIString

libs/main/core/pistringlist.h

@@ -77,7 +77,7 @@ public:
 
 	//! \brief Trim all strings
 	//! \details Example: \snippet pistring.cpp PIStringList::trim
-	PIStringList & trim() {for (uint i = 0; i < size(); ++i) at(i).trim(); return *this;}
+	PIStringList & trim() {for (uint i = 0; i < size(); ++i) (*this)[i].trim(); return *this;}
 
 	//! Return sum of lengths of all strings
 	uint contentSize() {uint s = 0; for (uint i = 0; i < size(); ++i) s += at(i).size(); return s;}