db-meta: name resolver recognizes track ids

The db-meta.cpp tool now loads the current index when the tool is started,
regardless of whether metadata is changed or not. The index is used to lookup
a persistent track id first. If none is found, the tool falls back to the
structure-based name resolver of db/Structure.
db-list: added -v (verbose) option

The db-list.cpp tool now prints its additional information ("# index ...") only
if the --verbose/-v option is passed on the command line. The information is
written to standard output now. In addition, the permanent track id shown is
abbreviated by the standard nice_hash() call to make the list more readable.
renamed Track::Format to Track::Blob

Calling the different binary versions of a track "blobs" should be less
confusing than going for "formats".
fixed db/file/Track's format parsing

The class in db/file/Track.hpp had a bug in the code parsing the format field.
The trailing whitespace after the format before the separator (" -- ") was
added to the format field.
added db-blob.cpp

Tool provides functions to display and modify a track's blobs. Particularly
useful to change the format or original name of a blob, and the only way to
actually add or remove new blogs. A conversion tool might use this command
to list tracks which lack a certain format, then fetch the blob from the
database, converting it to the desired format and adding the resulting blob
back to the track.