Remove the constants that assume a base unit in favor of explicit
x_per_y constants.
nanosecond calendar timestamps now use i128 for the type. This affects
fs.File.Stat, std.time.nanoTimestamp, and fs.File.updateTimes.
calendar timestamps are now signed, because the value can be less than
the epoch (the user can set their computer time to whatever they wish).
implement std.os.clock_gettime for Windows when clock id is
CLOCK_CALENDAR.
* `std.Buffer.print` is removed; use `buffer.outStream().print`
* `std.fmt.count` returns a `u64`
* `std.Fifo.print` is removed; use `fifo.outStream().print`
* `std.fmt.bufPrint` error is renamed from `BufferTooSmall`
to `NoSpaceLeft` to match `std.os.write`.
* `std.io.FixedBufferStream.getWritten` returns mutable buffer
if the buffer is mutable.
Thanks to the Windows Process Environment Block, it is possible to
obtain handles to the standard input, output, and error streams without
possibility of failure.
* use erase rest of line escape code.
* use `stderr.supportsAnsiEscapeCodes` rather than `isTty`.
* respect `--color off`
* avoid unnecessary recursion
* add `Progress.log`
* disable the progress std lib test since it's noisy and uses
`time.sleep()`.
* enable/integrate progress printing with the default test runner
