Make BDB optional.

See FIXME's in vips code

When using BDB,
	Can I reuse DB so I don't have to reread metadata?
	Otherwise, should DB deleted?

Memory analysis USE TINYSQL OR BDB:
Heap size is too big.
After reading all files in Storage/Music, heap is 6MB (lately 7,413,760
                                                       on MacBook)

After iTunes retrieves list of songs, heap is 16MB
iTunes retrieval creates 105,427 GNodes (dmap_structure_add)
                 creates 4,217,080 DMAPStructureItem bytes	
                 creates 4,217,080 GNode bytes	
		 creates 356,622 data bytes
2419 songs.
On OpenWRT, heap is 10.6MB, ps ax shows 27,712 RSS, 9.9MB swap used

Entire DMAP structure must be build before serializing and sending. Can
we break this up? See _dmap_share_message_set_from_dmap_structure and
dmap_structure_serialize.

Strings are copied a few times, but this does not seem to be as big a
problem as the GNode / DMAPStructureItem overhead.
	dmapd:dmapd-daap-record.c: g_value_set_string -> g_value_set_static_string
	libdmapsharing:dmap-structure.c: same as above.
	
==============================================================================

Review:
av-meta-reader-gst.c
av-meta-reader-gst.h
av-meta-reader.c
db-builder-gdir.c
db-builder.c
dmapd-daap-record-factory.c
dmapd-daap-record.c
dmapd-daap-record.h
dmapd-dmap-container-db.c
dmapd-dmap-container-db.h
dmapd-dmap-container-record.c
dmapd-dmap-container-record.h
dmapd-dmap-db.c
dmapd-dpap-record-factory.c
dmapd-dpap-record-factory.h
dmapd-dpap-record.c
dmapd-dpap-record.h
dmapd.c
photo-meta-reader-graphicsmagick.c
photo-meta-reader-graphicsmagick.h
photo-meta-reader.c
usage_dmapd.c

*** Dynamically adjust database when files are added to directories.

*** Support playlists using totem-pl-parser.

*** Fix seeking (see libdmapsharing TODO)

Migrate command line parsing to dmapd.xml.

Update documentation in dmapd.xml.

GStreamer:
	- DV State change failed for /shared/Storage/Movies/2006 1707 Oak/2006_house_condition_5.dv Bugzilla #569924
	- Break up gstreamer packages (see OpenWRT example)

Why do some albums (e.g.: 2008 Landscape) appear blank?
