Edit mode: Element
Location: Elements list, after right clicking on more than one element.
Function name: Group
Function icon: Light green double cube?
Function action details:
Grouping would be nice for "saving" a selection of elements so they act as one big element when you transform it. Its also so it is easier to organise lots of elements. Grouped elements additionally should be able to be minimised in the list (like a folder containing files) to maintain readability.
Consider the Ctrl+G shortcut with this functionality