Expand println section

[mdinger]

The println! section should be expanded to include:

• print!
• println!
• format!
• {} vs {:?}
• {:b} and other formatting parameters
• Why doesn't {} work for vectors and generic containers?
• Explain {:#?} RFC 640

@crumblingstatue Note anything else that should be added. I'll add it to the list.

[crumblingstatue]

I agree that more chapters could be added in the "Formatted print" section.
However, the first introduction to println! should use fmt::Display for formatting, as that is the natural way of writing formatted output. fmt::Debug shouldn't be taught as the "default" way of writing formatted output, but it should certainly be mentioned, as it is a useful tool for debugging.

[mdinger]

reddit thread highlighting confusion usage of {:?} created.

[mdinger]

Added {:#?} to header. RFC 640 has landed: http://is.gd/hdfaHi

[mdinger]

#196 is very similar to this issue but has different suggestions

[coffeejunk]

It might be helpful to add a small paragraph about print! needing a flush() to immediately display text on stdout

(ref rust-lang/rust#23818)

[steveklabnik]

Looks like there's only one checkbox left; I'd be more than happy to mentor anyone who wants to work on this!

[maccoda]

@steveklabnik Looks like this one is also complete thanks to @vishalsodani 😄

[steveklabnik]

🎊