Unhandled Individual Tag

When trying to read a Gedcom file exported from [ancestry.de](https://www.ancestry.de/) the crate panics with multiple unhandled tags.

```
thread 'main' panicked at 'line 35: Unhandled Individual Tag: OCCU',
```

or
```
thread 'main' panicked at 'line 33: Unhandled Individual Tag: PROP',
```

maybe if the tag is unknown, it can just be skipped instead?

