Issues:

#| digiKam			| KPhotoAlbum
================================+========================================
1| tags in a single tree	| tags in separate categories,
 |    				| can be organized into graphs with
 |				| member groups
 |				|
2| single datetime for image	| startDate and endDate for image
 |      			|
3| maps directorys as albums	| any category can be a "virtual album"
 |    				|
4| can't handle images in	| can
 | base dir			|
 |				|
5| uses filename as label	| images can have any label
 |				|
6| has ranking for images	| doesn't
 |				|
7| doesn't have drawings	| has
 |				|

Solutions to make KPhotoAlbum more digiKam friendly:

1: * Restrict KPA member maps to be trees.
   * Make a digiKam rootlevel tag for each KPA category and for each
     other digiKam rootlevel tag make a KPA tag in some special
     category (e.g. "Various").
   * Somethings has to be done for naming also:
     KPA can't have two tags, which have same name in same category.
     Trees can have two same named tags in different subtrees.

2: Save KPA startDate to digiKam datetime field and endDate to
   somewhere else. Or save (startDate+endDate)/2 to digiKam field and
   endDate-startDate somewhere else.

3: Allow only "Folder" category to be selected as virtual album in
   KPA.

4: Block images from base dir in KPA.

5: Restrict image labels to filenames.

6: Don't touch digiKam ranking fields in KPA.

7: Save KPA drawings to some table not used in digiKam
