show hide shapes in ROI

[will-moore]

See https://trello.com/c/DtbhtoAA/81-show-hide-all-shapes-in-an-roi
from https://forum.image.sc/t/large-mask-roi-on-large-image/29200/7

To test:

• Find an image with multiple Shapes per ROI (or create in Insight)
• Check ROI checkbox to show/hide all shapes in the ROI
• Toggling individual Shape visibility should 'check' the ROI checkbox if All shapes in the ROI are checked (same behaviour as the "Show" checkbox at the top of the table).
• The "Show" checkbox at the top of the table should also continue to work as expected.

[mtbc]

Seems odd to me that when I first go to the ROI tab for multi-shape ROIs the "show"s for the shapes are all checked but the "show" for their ROI isn't. (If I uncheck a shape then check it again then the ROI is then checked too.)

[mtbc]

Otherwise seems to be working well for me!

[will-moore]

#278 (comment) should be fixed (ROI checkbox is initially checked)