Skin can now be panned.
Double-click on receptor needed surface offset calc.
Receptor paths now traverse membranes based on membrane configuration.
Reworking carrier from-to transmission-reception to allow crossing membranes.
Finished initial implementation of membranes and receptor / carrier interactions between membranes.
Updated about.
Added a few test receptor applets.
Permeability dialog.
Merge remote-tracking branch 'refs/remotes/origin/membrane-protocol-traversals'