UPC/EAN, ITF14: quiet zones, addongap; raster/vector: sync code, use double

backend/tests/README

@@ -44,10 +44,18 @@ To show debug info (if any), use '-d <flag>':
 
   ./test_dotcode -f input -i 2 -d 1
 
+(for other flags see <project-dir>/backend/tests/testcommon.h)
+
 To generate test data, use '-g':
 
   ./test_dotcode -f encode -g
 
+To run a test against BWIPP (if any), use '-d 128':
+
+  ./test_composite -d 128
+
+(see also <project-dir>/backend/tests/tools/run_bwipp_tests.sh)
+
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 To make with gcc sanitize, first set for libzint and make: