HNN Beta release, version 0.0.3

This is HNN's Beta release, version 0.0.3. In this release we have made the following changes:

1. The top menu is reorganized into these top-level categories: File, Edit, View, Simulation, About.
2. After each simulation is run, the average dipole (across trials) is overlayed in the dipole panel (non-selected simulations using dotted lines, selected/new simulation using solid line).
3. You can now select a specific simulation from the set that was run using the Simulation menu (Go to Previous or Ctrl-Z, Go to Next or Ctrl-Y), or through the drop-down box at the bottom of the GUI.
4. You can remove the currently selected simulation using the Remove Simulation button - this will remove it from further display.
5. Previous/non-selected simulation dipoles are drawn using a black dotted line while the new/currently selected simulation dipole is drawn using a black solid line.
6. Only the currently selected simulation has RMSE calculated (for comparison with data).
7. You can clear all simulations using menu Simulation -> Clear simulation(s).
8. External (non-simulation) dipole data is drawn using a solid color line.