Various improvements to hgettext

[ffaf1]

A number of improvements to hgettext utility:

1. There is now a test-suite using shellcheck.
2. Options are now parsed sensibly using optparse-applicative.
3. hgettext does not break on unicode.
4. Additional minor bugfixes.

Again I can squash the commits once review is done.

[ffaf1]

Rebased on master.

[ffaf1]

@portnov If you have got any question I am glad to answer!

If this gets merged, I can help #1 (by asking a reproducer and writing a test).

[portnov]

I'll try to look into it this week

[portnov]

Hello again.
Sorry for late reply.

I tried to build it with stack build and got

[3 of 3] Compiling Main      
                             
/home/portnov/src/haskell-gettext/exe/Main.hs:13:1: error:
    Could not find module ‘Data.Text.IO.Utf8’
    Use -v to see a list of the files searched for.
   |                         
13 | import qualified Data.Text.IO.Utf8 as Utf8

Maybe you need to change some library version?

[ffaf1]

The resolver was quite old, I have bumped it.

Can you try now?

[portnov]

Yes, now it builds, thanks!