BinIndex in flashcard csv to contain position in bin

[ralfw]

Currently the bin index in the flashcard csv only tells the bin, e.g. bin no. 2 -> "2". But which position is a card at in that bin?

A box can be rebuild from the csv file with the cards being in the right bin - but not at the right position. They would be put in bins in the order they are in the file.

This can be improved by adding the position of a card within a bin to the bin index upon export at the end of SyncCommand processing. Example: bin no. 2 + intra bin position 3 -> "2.3".

Usually the position would be ignored upon import. But if an import is supposed to "boot" a box from scratch the position could be used to bring the cards in the right order.