changed Buildings\Fluid\Storage\StratifiedEnhancedInternalHex.mo

Wrong connections between exchanger and tank.

Some python functions to understand changes effect : http://pastebin.com/RF5exTzX

Actual model :
            - Exchanger first segment always connected to last tank segment (bottom of the tank)
                ---> Exchanger top position has no effect
            - Connections of the exchanger are done from bottom to top tank segment
                ---> Reversed connections


New model :
            - Exchanger segments are connected to the tank according to exchanger position
            - Connections of the exchanger are done from top to bottom