Adapted and included position_dodgev from lionel-/ggstance with appropriate modifications to allow for yend to be dodged.
Much documentation is altered due to newer versions so I've not committed unrelated man files.
Added example to ggalt_examples vignette.
Additional dependency: plyr could probably be worked around.
Standard usage of geom_dumbbell not altered as far as I can tell.
Warnings introduced in check() due to undocumented arguments in position_dodgev.