Support more latex type

Like 

Support \begin{gathered} \hfill \\ \hfill \\ \end{gathered} for `EscapeRows`:

```
\[\begin{gathered}
 1111 \hfill \\
 2222 \hfill \\ 
\end{gathered
} \]
\[\begin{array}{ l}
1111\\
2222
\end{array}\]
```