Translateable behavior properties

[OndrejVasicek]

When opt-in the Use Translatable Behavior checkbox, some additional code is generated to the model.
The main point of the Translatable Behavior is bring the attributes from "language tables" to the main model via magic properties.
The generator already have the list of attributes, so it would be great if it could generate PHPDOC for the relevant properties to achieve auto-completion for IDE

I tried to make the changes, it works for me, hope I didn't break anything. It should be quite small but helpful change.

[schmunk42]

Since it changes the return value of a protected method, it might break BC for custom generators.

Our proposal would be to add an additional index like fieldDefinitions to the return array which contains the names and types (shouldn't this be actually phpType?) - like the changes in this PR. And keep fields as it was.

WDYT?

CC: @eluhr @handcode