Assign uri from string to text

[sirex]

Usually uri is added to the text property, for example:

model	property	type	uri
City
	name	text	dcterms:title
	name@en	string

But in order to avoide adding separate row, especially, when text property has only one language, it is more onvenient to add uri directly to string:

model	property	type	uri
City
	name@en	string	dcterms:title

This way, dcterms:title is automagically added to name.

This only applies to string properties, if they ar part of text property.

If several string properties of same text property has different uri, an error should be raised.