Implemented reflection, simple cache system and ensure methods.

Alright I created 3 things here:

• A DReflection class, which will have functions related to reflection
• A DInsurance class, which will have functions for ensuring stuff (like ensure a variable is a certain type or just throw an exception)
• A cache system which saves stuff in RAM so you don’t have to keep repeating a specific search (like searching all classes in a specific package)

plus, I needed a simple error handler so the user could tell whatever he wanted to happen in ensure functions, instead of just hardcoding a throw new IllegalArgumentException().