Use display width in precision

[vitaut]

Use display width in precision. For example:

fmt::print("{:.5}", "🐱🐱🐱");

should print

🐱🐱

[jolz]

fmt::print("{:.2}", "🐱🐱🐱");

does print

🐱🐱

an this matches printf-specification (but with unicode support - yeah) https://en.cppreference.com/w/cpp/io/c/fprintf ("Precision specifies the maximum number of bytes to be written.")

std::printf("%.2s", "abcde"); // prints "ab"

why change?

[vitaut]

🐱 has a width of 2: