V4 add extimginfo (#37)

* Added my old struct size tester cpp proj.
* Added transfercanceled event like PR #35.
* Renamed datatransferred event.
* Idea for getting EXT_IMAGEINFO in transferred event.
* Renamed twain const and platform classes to shorter name.
* First attempt at reading TW_INFO, probably not correct.

csizes/pch.cpp

@@ -0,0 +1,5 @@
+// pch.cpp: source file corresponding to the pre-compiled header
+
+#include "pch.h"
+
+// When you are using pre-compiled headers, this source file is necessary for compilation to succeed.