cli: Fix compilation without LANG/LC_ALL set

[zarybnicky]

Embedded files are now assumed to be UTF-8 independently of the system locale. This also replaces the file-embed dependency with Hledger.Cli.TH, where embedStringFile has been changed to assume UTF-8 (utf8_bom).

Compilation without a locale (e.g. in nix-shell --pure or docker run -it fedora:28 bash as @talex5 mentioned) now works without a problem.

I've also changed the nix: sections of stack.yamls to use pure nix shells, and added the required dependencies of happy/alex - stack build --nix works for all build configs. (I'm on NixOS, so I can't actually develop without --nix, and compiling in a pure shell is also a nice bonus.)

Fixes #420, #813. This is also a better solution to the closed #669.

[simonmichael]

@zarybnicky, thanks for making the build more robust. Could you perhaps:

• submit embedStringFileUtf8 upstream - it seems like a useful feature.
• include the notes above in the commit description(s)
• separate the nix/stack updates into their own commit (or, mention why they belong with this one)

[zarybnicky]

I've opened an upstream issue, snoyberg/file-embed#27. I've also added to the commit description, and removed the Nix-related changes (I might open another pull request later, it's nothing urgent, just a nice-to-have).

[simonmichael]

Thanks @zarybnicky. I guess we should do a shorter workaround with less code duplication following the suggestions on that issue.

[zarybnicky]

Oops, didn't mean to click that.

[zarybnicky]

Alright, third time's the charm. This version just replaces embedStringFile with embedFile, and uses Data.ByteString functions to print out the docs.

[simonmichael]

Great, I guess this fixes this and this and is ready for merge ?

[zarybnicky]

Yup, I think so.

[simonmichael]

Thanks!