+ check integroty of postscript files, for later use in automatized

tests.

pub/itest/checkIntegrity.ps

+    {Script run} stopped
+    {
+       (\n===> Integrity test failed: ) print Script print ( has error\n\n) print
+       handleerror
+       (ignore this error which only serves to force a return value of 1) /syntaxerror signalerror
+    }{
+       % script passed, now check the stack
+       count dup 0 eq {
+          pop (\n===> Integrity test passed: ) print Script print ( terminated normally\n\n) print
+       } {
+          (\n===> Integrity test failed: ) print Script print ( left ) print
+          3 string cvs print ( item(s) on stack\n\n) print
+          Script /syntaxerror signalerror
+       } ifelse
+    } ifelse
+    quit