- Format string is internally represented as a series of formatting
items. Items can be directly given to now-public `format::format`
function as well.
- Format string parser is separated to `format::strftime` module.
This is to allow for potentional alternative formatting syntaxes.
- `DelayedFormat` now receives an iterator for formatting items.
- Every type modulo `LocalResult` and `Offset` now implements
`std::fmt::String`, so `.to_string()` can be used.
The exact format has been changed for better looking output.
- `std::fmt::Show` are intended for "stricter" output,
which mostly means the strict ISO 8601 format.
`DelayedFormat` also implements this, but only for inspection.
- `Offset` should implement `Show` but can omit `String`.
The old `name` method is merged into `String` implementations.
- `num` dependency is gone. It was only used for floored division
and it is not hard to copy only that portion from num.
- `Duration + Date` (or so) was blocked by rust-lang/rust#7590,
which has been subsequently fixed.
- Removed unused `unsafe` checks.
Eunchong Yu
Kang Seonghoon