Previously, we enforced code page 850 for all console input and output,
which breaks with non-western scripts. Since more recent Windows shells
are able to display Unicode properly, this patch now enforces UTF-8 and
falls back to code page 850 only if UTF-8 is unsupported.
Non-Windows systems default to UTF-8, but can override the codec
by setting the LANG environment variable to something other than C.
Resolves#3049.