Imaging Planner tool initial version

This is the release of a new tool, the Imaging Planner. This tool helps users decide what to image, similar to what the Observation Planner is for observing.

Ideally one would have HIPS DSS Colored All Sky Survey enabled (in the View menu) and a local cache (DSS Offline Source) downloaded (see View -> HIPS -> HIPS Settings -> Cache). Having a quick HIPS/DSS implementation makes this tool a lot more fun.