RFC: [FLUID] Find usage of models within fluid / autocompletion

[nostadt]

I am aware that it may be a challenging task, yet it would be an amazing feature. Perhaps, there is a standard mapping. Model name equals variable name and in case you want to stick to a different variable name, it's possible to do a mapping in a configuration file or so. Address-Model could be used as billingAddress and shippingAddress, yet both are of type Address.

Autocompletion: I guess, I don't have to add anything.
Find usage: Helpful if you want to clean up models or rename a property during development-process.

It might be related to #231 and or #232

What do you think about this?