cubicweb-squareui #3450287 Display the right column in TheMainTemplate [validation pending]

actually the right column is juste ignored in TheMainTemplate.

prioritynormal
typebug
done in0.2.0
load0.300
load left0.000
closed by#e912f1af89b2 [views] put back the right column in TheMainTemplate (closes #3450287)
patch[views] put back the right column in TheMainTemplate (closes #3450287) [applied]