These take a numerator and denominator defining the unit in a fractions
of a second. Conversion is done in integers, meaning that these must
clamp when approaching numeric limits.
Copy parse() method from LibCore::DateTime::parse(). Augment the method
to handle parsing from GMT time. Fix incorrect handling of year in '%D'
format specifier. Remove all format specifiers related to time zones.
Copy relevant tests and add additional ones.
That's what this class really is; in fact that's what the first line of
the comment says it is.
This commit does not rename the main files, since those will contain
other time-related classes in a little bit.
This allows us to make all comparision operators on the class constexpr
without pulling in a bunch of boilerplate. We don't use the `<compare>`
header because it doesn't compile in the main serenity cross-build due
to the include paths to LibC being incompatible with how libc++ expects
them to be for clang builds.
In practice, this function does not take any perceptible amount of time.
However, this benchmark demonstrates that for extreme values, the
internal for-loop does matter.
