Add support for unicode width aligned

[mrbeardad]

• version: 7.1.2
• problem: fmt::format does not take into acount width of characters.

code

    std::cout << fmt::format("{:-<10}{}", "你好", "世界") << std::endl;
    std::cout << fmt::format("{:-<10}{}", "hello", "world") << std::endl;

expected

你好------世界
hello-----world

Actual results

你好--------世界
hello-----world

你 and 好 is 2 columns character. The source code of neovim may help you to implement this function.

[vitaut]

Improved width computation in 7e72673. It should now give the expected result. Thanks for reporting.