Support for more Kinship models desired

[hartenthaler]

At the moment only the Eskimo model is supported. We need support for more models.

Some languages, such as Turkish, Chinese, Vietnamese, Hungarian, Bulgarian, and several others are using relative age when describing relationships.

For example, in China the Sudanese kinship model is used

• If the proband is male, he calls "father-in-law" as "岳父" and "mother-in-law" as "岳母"; If the proband is a female, she calls "father-in-law" as "公公" and "mother-in-law" as "婆婆"。
• Uncle has five Titles: the father's elder brother is called 伯父, the father's younger brother is called 叔叔, the mother's brother is called 舅舅, the father's sister's spouse is called 姑父, and the mother's sister's spouse is called 姨父.

see webtrees forum by @olor