new: rewrite of CombineWay action
new: conflict resolution dialog for CombineWay, including conflicts for different relation memberships
cleanup: cleanup in OsmReader, reduces memory footprint and reduces parsing time
cleanup: made most of the public fields in OsmPrimitive @deprecated, added accessors and changed the code
cleanup: replaced usages of @deprecated constructors for ExtendedDialog
fixed #3208: Combine ways brokes relation order
WARNING: this changeset touches a lot of code all over the code base. "latest" might become slightly unstable in the next days. Also experience incompatibility issues with plugins in the next few days.