Adds a BiasOrigin, which operates in parallel with an existing Origin, such that the effective weights of the
two origins together are all of the same sign (as is normally the case with synaptic weights in the brain).
To be used in place of the Mac look & feel apple.laf.AquaTreeUI (and CUIAquaTree), which seem not to
respect differences in tree cell size, or to expand tree cells when they change size.