Initial directory structure.
Initial build of Barcode Writer
Added EAN13, UPC

Refactored BarcodeBase
Added Code 11 & Code 2of5

Modified base methods.
Renamed to better reflect barcode type
Extensive re-work around checksum calculation.
Added helpers to UPCE and UPCA
Added PostNet & CPC although untested.
Simplified width calculation.
Added Code93 and ExtendedCode3of9
Added Code2of5