Add finding similar audio by content

[qarmin]

Fixes #132

Fixed also bug with not using cache when reading tags in similar audio mode
Cache loading times should now be a little faster
Also cleaned some code - need to have some #[timed] proc macro to calculate how long took function

Not all files can be compared - Symphonia have problems with some music files - pdeljanov/Symphonia#124

Most of the features are already implemented(tested on i7 4770):

• Fingerprint calculating and caching - 2374 music files was calculated in 4:15 minutes(9 files/second)
• Comparing fingerprints - 5 million comparisons(2374*2374) was done in 2:34 minutes(35000 comparisons/second)
• Faster reference folder checking - instead doing testing all possible combinations of files(n * n), only files from reference folders are compared to other files(k * m) - with same number of files to check, minimal speedup is 4x.
• Tags for files with similar content are read
• Can choose mode, minimal number of seconds and also maximum difference in GUI

TODO in different PR:

• Add support for multiple configurations - rusty-chromaprint support for now 3-5 preset configurations