Fixed bug re copied files not having updated modification time.

As part of porting to Windows, a recent change used std.file.copy()
to copy files, rather than using the "cp" external command. Windows
doesn't seem to have an equivalent, so std.file.copy() seemed like the
way to go. Unfortunately it goes to some trouble to preserve time
time-stamps.

This change set adds a setTimes() call to set access and modification
times to the current time.