Parser errors out on empty CONT lines generated by geneology programs

I have several v7 GED files generated by geneology programs that have some blank continuation lines. Here is a minimal example that fails with the parser.

```
0 HEAD
1 GEDC
2 VERS 7.0
0 @I1@ INDI
1 NOTE This is a note
2 CONT
2 CONT with a blank line above
0 TRLR
```

I have a simple fix that I will submit as a pull request.
