Changed handling of electrodeMapping and manualElectrode parameters.
Changed project_parameters to have input for manualVoltages defined inside it.
Changed import_data to only create a 1-to-1 map from BEM-solver text files to .mat structures.
	Each simulation is stored in a .mat file containing a data structure called Simulation.
Changed get_trapping_field to import these structures without handling electrodeMapping and
	manualElectrode parameters
Changed expand_field to expand all electrodes without any mapping logic.
Changed trap_knobs to handle the electrodeMapping and manualElectrode logic.
Changed set_voltages into a function to reduce namespace polution in the matlab workspace.
Renamed set_dc -> multipole_set_dc
Created a pairing_up_toy_example script to show inconsistencies in old handling of electrode
pairing.
Changed pst_process_trap, dc_potential to be compatible with the changes.