Implement option -dstrokeadjust in order to get stroked stems and strokeadjustment

Implement option -dstrokeadjust in order to get stroked stems and strokeadjustment

This makes the stroke drawing primitives for long rounded rectangles
dependent on the setting of currentstrokeadjust.  As a result,
low-resolution bitmap devices (up to 150 dpi or so) will get stroke
adjustment applied automatically.  The option needs to get invoked
explicitly to get stroke adjustment for PDF, giving a large file size
increase and markedly better previews on a number of PDF previewers.