Only define dynamic methods if a real one is missing

[struan]

This updates the dynamic method generation code to loop over each key in the JSON and check for a method getter and if one is missing autogenerate a getter method. Previously we were checking for a setter method which now always fails as the real methods are getter only.

The code that uses any found setter has been removed.

This also adds an .id method to Entity.

Part of #54

[struan]

comments on closed PR :/

So, I think once the various PRs for adding additional methods are merged then in theory we don't need the dynamic code. The only reason I could see us needed it is if we were concerned about breaking code that other people had where they'd augmented the EP JSON but I image we do not in which case, I suspect that just removing the code and adding something in the Changelog is the way to go.

[struan]

However, being super nice the thing to do might be:

• something in the Changelog saying it's going away
• later version issuing deprecation warnings
• remove code