update Block

### current behavior:
File, Tree, Shell have alot of common methods

### how to fix:
move the common methods to the Block class and inherit from it

reference:
https://github.com/abdelwahabram/shed/blob/5519214028a14c99ea72047d1adf43fe6ccd598e/source/block.py#L3

Look at the Block class in source/block.py and the File, Tree, Shell classes to identify common methods. Move those methods to Block and update the other classes to inherit from Block. Run existing tests to ensure nothing breaks.

Vom Indexierungsmodell aus dem Issue-Text verfasst.