Fails parsing newlines in path

New lines in path leads to `NaN`'s or `undefined` in result.

```
$ svgo -v
0.3.6
$ cat a.svg 
<svg xmlns="http://www.w3.org/2000/svg" width="10" height="10"><path d="m0,0
0,10 10,0z" fill="red"/></svg>
$ svgo -i a.svg  -o -
<svg xmlns="http://www.w3.org/2000/svg" width="10" height="10"><path d="M0 0l10 10vundefinedz" fill="#f00"/></svg>
```
