reverted PIString[] operators

libs/main/core/pistring.h

@@ -100,7 +100,13 @@ public:
 	 * or execution \a data() or \a toByteArray().\n
 	 * Example: \snippet pistring.cpp PIString::char* */
 	operator const char*() {return data();}
-	
+
+	//! Return symbol at index "pos"
+	PIChar operator [](const int pos) const {return at(pos);}
+
+	//! Return reference to symbol at index "pos"
+	PIChar & operator [](const int pos) {return PIDeque<PIChar>::operator[](pos);}
+
 	//! Compare operator
 	bool operator ==(const PIString & str) const;