Update wire plot to plot putative synapses.

Putative synapse locations are recorded when the `syn_distance`
parameter is set in the `[system]` block of the configuration file.
Currently, all locations are stored where there is a distance
equal-or-less than the specified distance in the configuration file.
Hence, putative locations are even recorded in between of dendrites
of the same neuron. Post-hoc filtering can be done by the user.
Add examples/detailed_avoidance.

In this example structural overlaps are avoided through "detailed avoidance", that is, avoidance is achieved through strong avoidance over short distances by other structures. Currently limited to repulsion away from the nearest structure.

TODO: Update to avoidance through repulsion by all nearby structures