`array` options, `\vlines` and `\hlines` and some bugs

While
```
\begin{array}{lcr}
1 & 2 & 3 \\
4 & 5 & 6 \\
\end{array}
```
is parsed correctly,
```
\begin{array}{l cr}
1 & 2 & 3 \\\hline
& 5 & 6 \\
\end{array}
```
is not. I tried all of them separately.

Note three types of issues
- Array options should at least be normalized removing spaces. It crashes if it finds some space between `lcr` letters.
- `\hline` is not ignored when the first item in the next row is empty and crashes as well.
- `\hline`s seems to be ignored by default

Besides that, I want to do a simple Ruffini table for my students. I think these features could be added. I mean vlines, hlines, etc.

UPDATE: Could vertical and horizontal lines be added with `rowlines` and `columnlines` attributes?
```

```
this would render well in Firefox