Add T-SQL highlighting, part 1

Hi, this is my first pull request so I'm not sure how it all works but:
I've added T-SQL support. It requires a few more styles but the css file doesn't seem to be in your repo so I'm not sure where it should go.

```css
/**sql language **/

pre .command
{
    color: #0000ff;   
}

pre .field
{
    color: #cccccc;   
}

pre .function
{
    color: #ff00cc;
}
```

Feel free to reject this and I'll re-do it.

Thanks!