Better course schedule diff

[djmitche]

#1834 fixes the issue of multiple schedule update comments, but the comments themselves are still not very useful.

Let's try to do a smarter diff, that emphasizes the changes the PR makes and not comparison to the target times.

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Changes to Course Schedule

This PR changes the course schedule. The new schedule is shown below.

Fundamentals // Day 2 Morning

2 hours and 50 minutes (5 minutes longer)

• Welcome - 3 minutes
• Pattern Matching - 1 hour 5 minutes (5 minutes longer)
• Methods and Traits - 45 minutes
• Generics - 40 minutes

Fundamentals // Day 3 Morning

2 hours and 20 minutes (10 miutes longer)

• Welcome - 3 minutes
• Memory Management - 30 minutes (30 minutes shorter)
• Ownership - 40 minutes (new segment)
• Smart Pointers - 55 minutes

[mgeisler]

We removed the functionality in #2268 since it wasn't as useful as we had hoped. We can probably close this as well.