Docx reader: fix list number resumption for sublists. Closes #4324.

The first list item of a sublist should not resume numbering
from the number of the last sublist item of the same level,
if that sublist was a sublist of a different list item.

That is, we should not get:

```
1. one
   1. sub one
   2. sub two
2. two
   3. sub one
```

1 files changed, 0 insertions, 0 deletions

diff --git a/test/docx/lists_sublist_reset.docx b/test/docx/lists_sublist_reset.docx
new file mode 100644
index 000000000..d4bf73852
--- /dev/null
+++ b/test/docx/lists_sublist_reset.docx