calculate the id of item with the crc32 of the file path
Merge branch 'vfs_item_id_crc32' into integration
include linux headers for crc32
Merge branch 'vfs_item_id_crc32' into integration
rename virtual_dir callbacks with dlna prefix (instead upnp)
add --disable-libupnp option to configure

with --disable-libupnp, Makefile will build the internal libupnp.
Otherwise, configure check if the standard libupnp is availlable.
check libupnp and redefine cflags
 set wrapper between standard libupnp and local libupnp
add wrapper between standard http VirtualDir (libupnp) and local
Merge branch 'external_libupnp' into integration

Conflicts:
	configure
missing header file

stdio.h was included by some libupnp headers file.
As cds.c uses *printf functions the file must to include the header file.
depends build, needs to have the optional CFLAGS.

to build depends the same flags have to be use to build the objects.
change libupnp flags
Merge branch 'external_libupnp' into integration
check "artist" keyword if "author" is not availlable
Merge branch 'artist_idtag' into integration
get_metadata and get_properties become profile callback

As the properties and metadata denpends of the media profile and the tools to probe the profile, they become callback of the static pointer of profile.
Merge branch 'ffmpeg_optional' into integration

Conflicts:
	src/dlna.h
	src/profiles.c
checks if callback is available before to use it.
stat return 0 if file is available
Merge branch 'ffmpeg_optional' into integration

Conflicts:
	src/profiles.c