Different files of the same track aren't merged in same track

[NoMore201]

Problem description

Adding two files of the same track will generate two different track objects, each one with a different resource.

Steps to reproduce

For simplicity, just copy a track in a test folder and make a duplicate, for example

mkdir test-music
cd test-music
cp /path/to/mytrack.mp3 .
cp mytrack.mp3 mytrack-two.mp3

Then

1 - Set test folder in teriscore.conf
2 - Run mediascanner with the new folder
3 - Start tersicore

Expected result

Tersicore should generate a single track object with two different resources

Actual result

Tersicore generate two different tracks

Possible solution

The problem is in this part of the code

tersicore/tersicore/mediascanner.py

Lines 32 to 38 in e496d64

	def update_resource(session, path):
	res = get_resource(session, path)
	if res is None:
	res = Resource()
	res.track = Track()
	parse_resource(res, path)
	session.add(res)

To check if a track exists, tersicore will check if an entry with the same path exists in the DB. But this is not enough, since we can have different files in different paths for the same track. IMO a good solution is to generate track UUID using an hash of toLowerCase(title) + toLowerCase(album) + toLowerCase(artist), rather than generating a random one. In this way the second file will have the same UUID as the first, and it will be merged in the first track as an additional resource.