- Twine, StringRef, Format, and NativeFormatting have been removed
- Logging now uses fmtlib style formatting
- Nearly all uses of wpi::outs/errs have been replaced with fmt::print() or
std::puts()/std::fputs() (for unformatted strings).
- A wpi/fmt/raw_ostream.h header has been added to enable
fmt::print() with wpi::raw_ostream
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 old headers were moved into folders because doing so avoids polluting
the system include directories.
Folder names were also normalized to lowercase.
