It usually generates slower code than manual handling.

* - try fixing the warning "chrono.h:1217:37: warning: conversion from 'std::make_unsigned<long long int>::type' {aka 'long long unsigned int'} to 'size_t' {aka 'unsigned int'} may change value [-Wconversion]" by casting int to size_t (occurs when cross-compiling to Raspberry Pi ARMv7)

* - remove call to to_unsigned() because using static_cast<size_t> is enough

* Adding comments for range formatting.

* Adding missing quotes

* Supporting nested format specs for ranges.

* I dedicate this commit to Eric Niebler.

* clang-format

* PR comments.

* throw -> FMT_THROW

* Need to map every element too.

* Clarifying uncvref_type

* Trying to add a workaround for MSVC.

* Fix #2681 - Make detail::print handle UTF-8

* Okay, let's do this Windows-only

* drop extra \0

* yay we can throw!

* Fix endianness bug in write_digit2_separated

* Move endianness check to compile time if it possible

* Turn 8 into a constant

this fixes a breaking ABI change that was introduce in the upgrade from
8.0.1 to 8.1.0.

Fixes #2695.