- Compile-able with MS-VC6

- Compile-able with MS-VC2015+QT5.18
- transbarency in TCL backend
- correct TCL demo
- README changes

backend_tcl/demo/demo.tcl

@@ -52,7 +52,7 @@ proc Generate {} {
 	::zintimg blank
 	::zintimg configure -width 0 -height 0
 	catch {
-	    zint encode [.e get] ::zintimg -barcode [.c get] -scale $sx {*}[.o get]} e]
+	    zint encode [.e get] ::zintimg -barcode [.c get] -scale $sx {*}[.o get]
 	}
     }
 }