I've mad a mod that does a number of things. First, it fixes all the doubles of buildings, cleans the code, and fixes some abilities (granary, war college). It also adds +1 trade route for each market (might be unbalanced lategame).
NOTE: This is a CORE MODIFICATION, not a normal mod. Maybe it can be used as a normal mod but it's intended to replace the core files because of some major bugs I found.
Let me know how it works!