std.stdio: clean imports

fix

fix

remove string import

uncomment unittest

update Flag!"KeepTerminator" usage

fix typo

fix errors

private format

fix yes/no

update private format

format workaround

renamed flags to lower case
specialization of std.typecons.Proxy for classes

using selective import

remove nonsense code

integration of static this.

add a comment

avoiding some warnings

remove InvalidTypeException

improve readability