Regions features

[keflavich]

There are several regions features I'd like to see in CARTA, many analogous to ds9 features. I suggest we use this thread as a place to keep a wishlist.

• different regions for each image. At least, control of which regions are associated with each image
• easy control over multiple regions:
  • grouped manipulation (moving, deleting)
  • creation of linked regions, include/exclude regions
  • property editing
• region load interface that defaults to a different directory than the images
• wildcards should work in the region write interface