Better cloning for td-builder.service.ts

[relu91]

As introduced by #52, the td-builder.service.ts now use the usual trick of JSON.stringify and parse to clone the TD model and generate a valid Thing Description. Is there a better way to achieve this? Is this really performance critical?

Tracking

zion/src/introduction/td-builder.service.ts

Lines 25 to 26 in cc5a16a

	// FIXME: Get rid of this workaround.
	const clonedModel = JSON.parse(JSON.stringify(model));