update all unit tests, fix bug with unterminated escape, updated multiline parsing, refactored some code, removed unused code

include/ss/converter.hpp

@@ -198,6 +198,10 @@ private:
         return splitter_.resplit(new_line, new_size, delim);
     }
 
+    size_t size_shifted() {
+        return splitter_.size_shifted();
+    }
+
     ////////////////
     // error
     ////////////////