Grouping

[kmcurry]

When I'm 3Scaping I want to manipulate multiple things at once as a group.

Requires #158

Scenario: I select 3 things. I hit Command + G, a group icon or perform a gesture to group them. The three things can then be selected and moved, manipulated as one thing.

For selection: I click once on anything in a group (or the negative space?) and I select the group. All actions are on the group. When I click again on a thing in the group (not neg space) I select the single thing. All actions are on the single thing.

Group has slightly different meanings in different contexts or at least multiple interpretations. For example, should scaling a group of 3 objects equally scale each object as well maintaining as the space between objects or does it scale objects that grow to overlap?