Change data/loader syntax

[kantord]

Instead of having attr:loader attr:query etc., data should be modified like this:

• Data should be an array
• If data x is not an array, it's interpreted as [x]

Each element in the array can be

• A "magic" string that is parsed into an array of loader objects
• An object with one key and one value (e. q. {graphQl: ["asdf"]} etc.)

The first loader receives undefined as input argument. All the other loaders receive the result of the first loader as argument.