Improves the APIs for various prebuilt subsystems (PIDSubsystem, TrapezoidProfileSubsystem, ProfiledPIDSubsystem). Addresses #2128, and also changes the rather cumbersome getSetpoint API to a more intuitive setSetpoint one. Updates examples to match.
Since there is a new version of GearsBot using the new command-based
API, the old GearsBot is just removed.
PR #1842 is being included to verify this PR is correct.
The old headers were moved into folders because doing so avoids polluting
the system include directories.
Folder names were also normalized to lowercase.