djot-0.1.0.0: test/math.test

Math goes in verbatim spans prefixed with either `$` (for
inline math) or `$$` (for display math).

```
$`e=mc^2`
.
<p><span class="math inline">\(e=mc^2\)</span></p>
```

```
My equation: $`e=mc^2`
.
<p>My equation: <span class="math inline">\(e=mc^2\)</span></p>
```

```
$$`e=mc^2`
.
<p><span class="math display">\[e=mc^2\]</span></p>
```

```
My equation: $$`e=mc^2`
.
<p>My equation: <span class="math display">\[e=mc^2\]</span></p>
```

Newlines are allowed, just as in verbatim:

```
$`e=
mc^2`
.
<p><span class="math inline">\(e=
mc^2\)</span></p>
```

`$` characters are allowed inside:

```
$`e=\text{the number $\pi$}`
.
<p><span class="math inline">\(e=\text{the number $\pi$}\)</span></p>
```