Enhance gridding

[local-minimum]

Gridding could attempt to use heuristics or history about grids for specific fixtures to assist gridding and/or warn users when grids may be placed in suspicious ways.

[skymandr]

When evaluating the options of where to put the grid center and what grid column/row spacing to use, add a heuristic cost for all colonies that would en up outside the image for each center-option.