electrode position filtering

patrick wrote a function to select an ROI based on electrode coordinates. might be useful to add here.

```
def get_data_in_bounds(data, acq_channels, elec_pos, min_x, min_y, max_x, max_y):
positions = np.argwhere(
(elec_pos[:, 0] >= min_x) &
(elec_pos[:, 0] <= max_x) &
(elec_pos[:, 1] >= min_y) &
(elec_pos[:, 1] <= max_y)
)
data_idx = acq_channels[positions] - 1
return data[:, :, data_idx[:, 0]]
```