Bk/rename day and month

[bryankeller]

Details

Many people are confused by the purpose of Day. Is it like my custom Day type used in my company's codebase? Is it like Date? Is it like DateComponents? Why can't I initialize it myself?

Day (and Month) are really just small structs that contain some components of a day / month. They're much more similar to DateComponents, but because they're only created internally and vended out through the public API of the calendar, we can guarantee a few things:

• They're Orderable in relation to any other date that's vended out of the same CalendarView instance
• They're valid for whatever Calendar and date range the CalendarView was initialized with

People should treat them like read-only bags of data. They just exist as a way for CalendarView to pass some data back to API consumers. Hopefully these new names and documentation tweaks help clarify that a bit, and people stop asking why their initializers aren't public.

Related Issue

N/A

Motivation and Context

Improve API and make it more self-documenting.

How Has This Been Tested

Example app

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[bryankeller]

FYI after this is merged, I'll bump everything to v2.0.0🥳