[Development] Should we change the default codec of QTextStream to UTF-8?

[1+1=2]

Hi all,

It might be a bit late for 5.0.

But Qt 5 have started to enforce that source code file must be UTF-8.
So perhaps it make sense to change the default codec of QTextStream to
UTF-8.
This won't break many things, as the old behavior can be obtained by
calling QTextStream::setCodec().
I have push a commit for it: https://codereview.qt-project.org/#change,26985

In addition, this will  improve the unicode handling ability of Qt
tools with using bootstrap. Otherwise, tools such as qmake can not
deal with UTF-8 encoded files.

Any idea?

Regards,

Debao