Checkins dependent on Project

If the project is destroyed, the checkins will be too.
Projects dependent on User

If the User is destroyed, the Projects will be too
Checkin view modifications

Some whitespace rejiggering, but notably:

• Modified the new checkin page
• Heavily modified the show checkin page
Added Project ID to Checkins

How did I miss this?
Showing a list of checkins on the project page

Basic functionality complete y’all