Milky/multi feature copypaste

[milkmanmatty]

Builds upon #14 feature bandbox

Main Functionality

Add ability to copy and paste multiple features selected by bandbox selection. The paste operation is safe and will only place features that are not blocked.

Functional Requirements:

• Single Features copy&paste is unchanged and behaves as usual.
• Section tile copy&paste is unchanged and behaves as usual.
• Multiple Features selected are copied without issue.
• Multiple copied Features retain their relative offsets when pasted.
• Features that would be pasted with an invalid relative offset (e.g. offset would place feature off-map) are not placed and do not cause an error.
• All of the multiple pasted Features remain selected.