Don't buffer the changes to the console colors.

After a Console.Write/Writeln that uses colors a call to
ConsoleColorScope::LeaveScope() is made to restore m_old_color. This
restoration command stays buffered until a full line is printed. In the
meantime any console message that happens will use the old coloring
and if the program happens to crash the console would keep using the
color of the last colored text that was printed.
Merge pull request #391 from micove/flush-color-reset

Don't buffer the changes to the console colors.