Code generation based on OpenAPI

[davidtsadler]

Code generation for the SDK will use the OpenAPI files that eBay provide for the Restful services. Code generation for the XML services will use custom OpenAPI files created for the SDK.

The solution will be PHP based instead of the current XSLT solution.

[michabbb]

@davidtsadler thanks a lot for the infos. Because my main business is based on the trading api, it would be nice to know if you plan anything new For these APIs too? Because if you stay at the old way with your makefile, I still need some little infos howto generate these files so that we (not only me), are able to update the object files, that would be really great. As already mentioned, there is no need for a super detailed website, as u usually do (what is really great), in this case a short list of todos would be a nice start. Maybe you find a few minutes to write some lines down, that would help us a lot. People regularly submit pull requests, because they don't know that you generate these files, so knowing howto update those, would give everybody more freedom. And of course, we could help you better.

Thanks!