allow specifying document name (title) and description

Adds two new options: `documentName` and `documentDescription`, that set the appropriate tags of the root document. This is useful for providing meaningful titles and descriptions for applications like google-earth.

The PR includes unit tests. Coverage is still at 4x100% ;)

```
Statements   : 100% ( 58/58 )
Branches     : 100% ( 23/23 )
Functions    : 100% ( 29/29 )
Lines        : 100% ( 55/55 )
```