Improvements: Attributes, Readme, Code-Documentation

[anianweber]

• Refactor the usage of attribute vs. the usage of classes in the InlineStyleEditing.js und BlockStyleEditing.js code to get a clear distinction of the 2 implementations

  • Alternatively refactor them to be generic and unspecific to one or the other implementation
  • Avoid unclear conditional logic, like: https://github.com/techdivision/ckstyles/blob/master/Resources/Private/JavaScript/CkStyles/src/BlockStyleEditing.js#L39

• Improve Readme to further clarify the use case of setting classes vs. the use case of setting other attributes

• Add additional inline documentation to the code to further clarify whats happening (especially considering the complex API of CkEditor 5)

[mhsdesign]

i can aggree with that :P Code doesnt read that well, when i looked at it the first time ^^

I may be able to help

edit: #32 🎉