templatekw: change {file_copies} behaviour, add {file_copies_switch}
{file_copies} template now displays file copies with or without the --copies
switch being set. A new {file_copies_switch} template implements the former
behaviour.
#!/bin/sh
hg init
python -c 'print "confuse str.splitlines\nembedded\rnewline"' > a
hg ci -Ama -d '1 0'
echo clean diff >> a
hg ci -mb -d '2 0'
hg diff -r0 -r1