Overhaul of Config Parser & Calendar Offset

[Timm638]

This pull request changes the script in following ways:

• Overhauled the config parser (not backward compatible!) to reduce the tedium of writing a config:
  • Added the ability to read date ranges (e. g. 01.10.2024-05.10.2024,name,feiertag)
  • Added the ability to add periodical returning dates (e. g. 12.01.2024~2w~31.12.2024,Loscher,loscher)
• The calendar can be offset by a amount of months, allowing for calendars e. g. ranging from 10.2024 - 09.2025
• Added optional ability to fetch german holidays from holidays package (Looking at you religious holidays ლ(ಠ益ಠ)ლ)
• Refactored code to decrease code repetition
• To keep the code readability the same, object oriented programming has been implemented (\sarcasm)
• Overhauled read me to contain hopefully noob-proof quick start guide