port FLAC example to its own package

[SimonDanisch]

FLAC isn't installed on my pc which is why the tests fail... No biggy I guess, but should we think about using FLAC.jl, which is a binarybuilder for FLAC?
https://github.com/dmbates/FLAC.jl

[ararslan]

It appears that FLAC.jl was purged from the General registry. (I forget what the conditions were for being purged, but a purge happened recently.) So we'd need to use something else, or just use the BuilderBuilder-built FLAC binaries ourselves.

[SimonDanisch]

It is super old indeed -.- But maybe one of these packages, that are easy to make work again...
We could possibly regenerate the wrapper with Clang - but I'm not sure how worthwhile this is ;)

[ararslan]

I think at one point @jrevels said he wanted to move the integrations for different codecs into separate packages or something like that, but I could be mistaken. That would make sense to me, then a package for FLAC integration could use the binaries directly or take a dependency on some revived version of FLAC.jl. Also that means that someone who needed FLAC integration (i.e. not us) could put the effort into making it happen 😛

[jrevels]

A note for the future: it would also be nice for the FLAC example to demonstrate support for the relevant deserialize_lpcm(..., sample_offset, sample_count) method, since FLAC itself has built-in seek support.

[ericphanson]

looks like this was done in #89

edit: no, I misunderstood the scope of the issue