Add support for coordinates in Adobe format in XMP tags

[malconsei]

• exif parser: Add support for Adobe coordinates
• exiftool parser: Try to get coordinates in the XMP-exif namespace, too

[ptpt]

These two cases are doesn't share much in common. It feels easier to understand if you separate them. How about this:

def _extract_lon_lat_numeric():
    # the numeric case
    pass

def _extract_lon_lat_adobe():
    # the adobe case
    pass

def extract_lon_lat():
    lon_lat = self._extract_lon_lat_numeric()
    if lon_lat is not None:
        return lon_lat

    lon_lat = self. _extract_lon_lat_adobe()
    if lon_lat is not None:
        return lon_lat

    return None

[ptpt]

Accept to unblock.

[ptpt]

Do we need to apply the reference for the adobe value again? I thought adobe has NSEW parsed from its own format so it doesn't have to respect this one here?

[malconsei]

Correct, the Adobe coords already have the right sign, that's why I added the check on lon/lat > 0 - to avoid multiplying them by -1 again. But yeah, it's hacky, I'll make it more explicit :)

[ptpt]

Why not separating them? So adoble values don't need to respect the ref tags. See my proposal above.