A lot of these are breaking changes. frc::Timer was replaced with the
contents of frc2::Timer. The others were in-place argument changes or
removing deprecated non-unit overloads.
The current hasPeriodPassed() function is confusing. In preparation for deprecating it,
add new advanceIfElapsed() function with same functionality and hasElapsed() function
which only checks that the time period has elapsed and does not advance the timer.
Also fix a couple of incorrect usages of hasPeriodPassed().
- Remove use of std::set. The only place std::set was actually used was in ParallelRaceGroup,
but this was of minimal utility as ParallelRaceGroup checked for duplicate subsystem
requirements, so it would be very unusual to end up with duplicate commands
in any case; replaced it with a vector.
- Remove use of std::unordered_map except for SelectCommand. Replaced with vector.
- Use pImpl idiom for CommandScheduler
- Minimize include files (remove unnecessary ones)
- Reformat include file order for consistency
