Sets default values for graphical parameters when initializing
a graphics device.
USAGE:
Device.Default(name)
OPTIONAL ARGUMENTS:
name:
character string giving the name of the device.
SIDE EFFECTS:
the session data objects .Device and .Devices are created or modified.
DETAILS:
This function is called by all device driver functions
to set up default values for graphical parameters.
At present, it sets axis styles to "r" and sets margin size.
The rationale for this function is that you can define
your own version and thus control the default parameter values for the
various devices you use.