Sagittal control

[kouichi-c-nakamura]

A fix for an issue mentioned here:
#28 (comment)

Symptom

When using AtlasTransformBrowser, the command window shows the Control message that explains keyboard shortcuts.
However, the Navigation section contained some errors and needed to reflect plane.

Changes

• This pull request changed the message content so that the message reflects the plane variable, coronal, 'sagittalortransverse`.
• The down key is assigned for moving across atlas images while the left key is used for changing the slice number which corresponds to Slice Viewer. This was not clear, so I tried to make it clearer.

eg. plane = sagittal
Navigation:
up: scroll through D/V angles (for sagittal sections)
right: scroll through A/P angles (for sagittal sections)
down: scroll through M/L atlas slices
left: scroll for Slice Viewer
scroll: move between slices or angles

[philshams]

Makes a lot of sense, thanks for this.

[kouichi-c-nakamura]

Thanks a lot for adopting this!