Miscellaneous improvements

[Narzgul]

Let me start with excusing myself for this undocumented contribution and I am willing to continue explaining my changes if necessary.

This is the code I use to communicate to the Webuntis-API in my HUntis App. It is forked from this project and many of the changes are for adherence to the flutter code-style.

I however also have added some changes that could potentially clash with the usage of webuntis in other schools / institutions. Since I have only developed my app and by extension added to this project only with access to my schools system I can not check if it works for others.

I want to finish with expressing my gratitude to @IsAvaible for providing this project, because my app would not have been possible without it, which is why I want to give back by contributing!

[IsAvaible]

Hey @Narzgul,

Thank you for your interest in my project! I have looked into the changes you have made and have found some issues that would need to be resolved before I could consider merging your pull request:

1. You introduced three unused imports ('package:flutter/material.dart', 'package:huntis/main.dart', 'package:intl/intl.dart'), one of which is part of your personal project ( 'package:huntis/main.dart').
2. Most of your changes are of a stylistic / formatting nature. While I do agree, that some parts of the original code are too dense and hard to read, line splits like [untis.dart - line:574] feel unnecessary to me. Maybe we could agree on a code style / formatting tool to use?
3. I have found one snippet that seems to impact the behavior of the code [untis.dart - line:150-243]. Some changes seem to be specific to your project (e.g. [untis.dart - line:200]). Could you elaborate on what exactly the purpose of the snippet is?

Have a nice Sunday!