Should NeoFormatter and TypedNeoFormatter have default generics?

[sffc]

Currently if you want a time formatter you need to explicitly set the calendar type to NeverCalendar / ().

This raises the general question, should they have default generics?

The time formatter specific concern can also be addressed by

1. Make a type alias such as pub type TimeFormatter
2. Make format_time imply this bound

@Manishearth @robertbastian

[Manishearth]

I don't really think there's a sensible "default" here. I think TimeFormatter is fine. I also think adding the bound may work, though it would be nice if DateTimeFormatter could format_time too.

[sffc]

This currently works:

TypedFormatter::try_new(
  locale,
  fieldset::YMD::with_length(Medium)
)
.format(Date::try_new_gregorian_date(...))

This currently requires an explicit NeverCalendar:

TypedFormatter::<NeverCalendar, _>::try_new(
  locale,
  fieldset::HM::with_length(Medium)
)
.format(Time::try_new(...))

If we had format_time (#5269 (comment)), the type inference should work because the function would be defined on Formatter<NeverCalendar>

TypedFormatter::try_new(
  locale,
  fieldset::HM::with_length(Medium)
)
.format_time(Time::try_new(...))

[sffc]

What would pub type TimeFormatter map to?

pub type TimeFormatter<FSet> = TypedFormatter<NeverCalendar, FSet>
pub type TimeFormatter<FSet> = Formatter<FSet>
pub type TimeFormatter = TypedFormatter<NeverCalendar, TimeSkeleton>

[sffc]

I don't consider this a 2.0-beta blocker.