Partition dimensions: plug the Edition split position preference to the Edition hyperlink command

Locations:

• org.txm.edition.rcp.handlers.OpenEdition.computeSplitRatioPosition(TXMEditor)
• org.txm.partition.rcp.chartsengine.events.PartitionDimensionsCallback.processEvent(Object, int, Object)

Defines if it's worth having a different preference by concerned result (Partition Dimensions, Concordance, etc.).