Need more flexible configuration passing.

[graphicore]

Currently there's no easy way to pass widget configuration to main.js. Especially configuration like featureDisplay.feaureItemsSetup is very dependent on the font and can't really be made generic. At the same time CSS class names configuration can be done in main.js.

We need a generic way to pass configuration from the document to the specimen initialization that can override configuration made centrally. For some examples, where the configuration can be nested objects, we need a way to merge the data.