zshrc: add an rless alias.

LESSOPEN can be very useful, but often one wants to read the raw contents of
a file.  Add an rless alias that does this.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
zshenv: use -f for less by default.

Avoid less complaining about binary files.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>