Sort families by date of marriage only if all dates of marriage for spouses at a level are know. If not use the default webtree order.

[zeezhao]

Describe the bug
This is related to the bug I discovered and mentioned here:

#39 (comment)

Families are being shown in random order, if marriage date is not filled and unknown.

To Reproduce
If any marriage date in a branch at a level is not set, it is causing a random order of families.

Expected behavior
The date condition should please be applied to Marriage date too i.e. if any marriage date in a branch at a level is not set, then default to original family order as originally set up in webtrees. Thanks

[zeezhao]

Hi. I can't test this as not got marriage dates. But I suspect it was also related to #39 and #43 issues discovered, that were subsequently fixed. Please confirm. Thanks.