Function insertSpace

Inserts space within sortedEvents. It does this by shifting events forward.

If start overlaps with existing item(s), overlappingPolicy is used:

• 'ignore': Event duration is not changed
• 'stretch': Events that overlap are stretched by length.

When considering overlap, both end is exclusive and start are considered exclusive.

Eg, if we have the event { start: 5, end: 10 }.

• insertSpace(data, 5, 1, ignore); // Would not be considered overlapping, but event would be shifted to { start: 6, end: 11 }
• insertSpace(data, 10, 1, ignore); // Would not be considered overlapping, event would remain { start: 5, end: 10 }
• insertSpace(data, 5, 1, stretch); // Would be considered overlapping, event shifted to { start: 6, end: 11 }
• insertSpace(data, 6, 1, stretch); // Would be considered overlapping, event would be stretched to { start: 5, end: 11 }