Entry & exit dimensions for eVars

[#1]

It would be great, to have entry & exit dimensions for eVars.

Without those, one may only rely on such dimesions for props, which work insufficiently for values longer than 100 chars. Especially in case of exit & entry page URL, which might be the exit & entry dimension, chars might be cut in many cases. Hence, those dimensions would only be truely useful in combination with eVars.