Feature request: support locales set in the system

I always use latin1 encoding in all my systems and all my file systems. On the other hand, I use task for many year now up to version 2.6. However, the code did corrode a bit and something like `task all` refuses to work now. So I always had a look at the upcoming v3 version.

However, it does not work correctly and I am not able to get it to work with German umlauts.

A `ü` will be convertet to `�` and so on. Even more, it is not possible to use any other chars than ASCII.

Migrating all my systems to utf-8 is not a option as that would break so many other stuff and making many files impossible to use anymore.

But this is exactly why there is locales. Mine is for example:
```
LANG=de_DE
LC_CTYPE=de_DE
LC_NUMERIC=de_DE
LC_TIME=de_DE
LC_COLLATE=de_DE
LC_MONETARY=de_CH
LC_MESSAGES=de_DE
LC_PAPER=de_DE
LC_NAME=de_DE
LC_ADDRESS=de_CH
LC_TELEPHONE=de_DE
LC_MEASUREMENT=de_DE
LC_IDENTIFICATION=de_DE
LC_ALL=
```

So I want to ask to care about the user set locales and not blindly convert anything to utf8 (It is even not proper utf8 if I see correct.)

If there is any that I can do, I'd like to do. I have good knowledge in C, moderate in C++ and excelent in perl but none in python.

I tried to find where the input/output is done in the code but I got lost. In my opinion it should be pretty easy to do the conversion in input/output.

Please consider that request a try. I would love to use task further on as it is exactly filling my needs.