Additions to print density corrections

Missed correcting values below 50 (-14 would produce -15 in the output etc).
diff --git a/ppdc/sample.drv b/ppdc/sample.drv
index b5cd99d..6ca0e82 100644
--- a/ppdc/sample.drv
+++ b/ppdc/sample.drv
@@ -450,20 +450,20 @@
     Option "inPrintDensity/Print Density" PickOne DocumentSetup 20.0
       *Choice "Default/Printer Default" "<</cupsCompression -1>>setpagedevice"
       Choice "-15/-15" "<</cupsCompression 0>>setpagedevice"
-      Choice "-14/-14" "<</cupsCompression 3>>setpagedevice"
-      Choice "-13/-13" "<</cupsCompression 6>>setpagedevice"
+      Choice "-14/-14" "<</cupsCompression 4>>setpagedevice"
+      Choice "-13/-13" "<</cupsCompression 7>>setpagedevice"
       Choice "-12/-12" "<</cupsCompression 10>>setpagedevice"
-      Choice "-11/-11" "<</cupsCompression 13>>setpagedevice"
-      Choice "-10/-10" "<</cupsCompression 16>>setpagedevice"
+      Choice "-11/-11" "<</cupsCompression 14>>setpagedevice"
+      Choice "-10/-10" "<</cupsCompression 17>>setpagedevice"
       Choice "-9/-9" "<</cupsCompression 20>>setpagedevice"
-      Choice "-8/-8" "<</cupsCompression 23>>setpagedevice"
-      Choice "-7/-7" "<</cupsCompression 26>>setpagedevice"
+      Choice "-8/-8" "<</cupsCompression 24>>setpagedevice"
+      Choice "-7/-7" "<</cupsCompression 27>>setpagedevice"
       Choice "-6/-6" "<</cupsCompression 30>>setpagedevice"
-      Choice "-5/-5" "<</cupsCompression 33>>setpagedevice"
-      Choice "-4/-4" "<</cupsCompression 36>>setpagedevice"
+      Choice "-5/-5" "<</cupsCompression 34>>setpagedevice"
+      Choice "-4/-4" "<</cupsCompression 37>>setpagedevice"
       Choice "-3/-3" "<</cupsCompression 40>>setpagedevice"
-      Choice "-2/-2" "<</cupsCompression 43>>setpagedevice"
-      Choice "-1/-1" "<</cupsCompression 46>>setpagedevice"
+      Choice "-2/-2" "<</cupsCompression 44>>setpagedevice"
+      Choice "-1/-1" "<</cupsCompression 47>>setpagedevice"
       Choice "0/0" "<</cupsCompression 50>>setpagedevice"
       Choice "1/1" "<</cupsCompression 54>>setpagedevice"
       Choice "2/2" "<</cupsCompression 57>>setpagedevice"