plgdiori: Get plot orientation 

DESCRIPTION:

    Get plot orientation parameter which is multiplied by 90 degrees to
    obtain the angle of rotation.  Note, arbitrary rotation parameters
    such as 0.2 (corresponding to 18 degrees) are possible, but the usual
    values for the rotation parameter are 0., 1., 2., and 3. corresponding
    to 0 degrees (landscape mode), 90 degrees (portrait mode), 180 degrees
    (seascape mode), and 270 degrees (upside-down mode). If plsdiori has
    not been called the default value pointed to by p_rot will be 0. 

SYNOPSIS:

plgdiori(p_rot)

ARGUMENTS:

    p_rot (PLFLT *, output) :     Pointer to orientation parameter.