Refactor the data schema

[KL13NT]

The current schema is difficult to maintain and use, and forces me to build mumbo jumbo code that is confusing and poor in performance. It's also difficult to get started with since it's difficult to document for onboarding.

The current schema is:

class Entry {
  origin: string;
  lastVisit: Date;
  firstVisit: Date;
  [year]: {
    [month]: {
      [day]: number
    }
  }
}

This schema is not properly built, doesn't adhere to any SOLID principles, difficult to maintain, and is difficult to maintain. The new schema is:

class Session {
  date: Date;
  duration: number;
}

class Entry {
  origin: string;
  lastVisit: Date;
  firstVisit: Date;
  sessions: Array<Session>;
}

This will require an overhaul of the codebase to use the new schema.

[KL13NT]

IDEA: Don't transform the datastore itself. Transform the representation by adding an abstraction layer that translates the datastore format into an application format, like an ODM.

[KL13NT]

This proves useless against the current data though. We're still in pre-v1.0.0, so it should be okay to nuke it all.