matrix: (1) Both `cellRect` (typically non-transparent) and `cellText` may trigger events, depending on both `matrix.triggerEvent`, `matrix.xxx.silent` and `matrix.xxx.label.silent` settings. By default (`matrix.triggerEvent:true`, `matrix.xxx.silent` and `matrix.xxx.label.silent` is undefined) cell text and non-transparent cell bg trigger event. (2) Modify event param: `name` is the final rendered text, `value` is the original input cell value in option. (3) Add visual test cases for `matrix.html`.