Create a map-based edit control for lat/long

[fisharebest]

See #4283

[hartenthaler]

I would be happy if this edit control would become reality because at the moment when adding coordinates to a _LOC record it is a bit painful using copy/paste from a web page where the coordinates can be found.

[webtrees-pesz]

I support this as well. In webtrees 1.7 it had already worked.