Support for building with GHC-8.2

[bezirg]

Currently, the library cannot be built with GHC-8.2 and its packages:

base-4.10.0.0
Cabal-2.0.0.2

[decentral1se]

PR's glady accepted @bezirg! I might take a stab if I get time.

[basvandijk]

@lwm how far did you get with this? I would also like to use packunused on GHC-8.2.

[decentral1se]

@basvandijk, nowhere really, enabled failing matrix builds on #34 to see what issues were and stopped there.

It's up to you!

[OlivierSohn]

I made it compile with GHC8.2.2, and added the support for the new kind of libs (sub libraries, foreign libraries) : #36

However I can't test it on my project (#35), so if anyone wants to try #36, feel free.