Date and time of AVNotes files should depend on EXIF data

[MiMoHo]

To know date and time of a photo is important and much more appropriate, when it is pulled from the EXIF data of images as files tend to get modified over time especially when they are copied from other sources to insert them into the map. Please make sure that a media's timestamp shows the correct date when it was taken. Only in case this data is missing, it may be helpful to rely on the file's timestamp instead of the missing EXIF data.