Added recording cut functionality

Runtime/Scripts/Timeline/GLTFRecorder.cs

@@ -199,6 +199,30 @@ public void SampleIfChanged(double time)
 						lastSample = value;
 					}
 				}
+
+				public void CutTrack(double start, double end)
+				{
+					var copySamples = new Dictionary<double, object>(samples);
+					samples.Clear();
+					bool isFirst = true;
+					foreach (var k in copySamples)
+					{
+						if (k.Key >= start && k.Key <= end)
+						{
+							if (isFirst)
+							{
+								samples.Add(0, k.Value);
+								isFirst = false;
+							}
+							else
+								samples.Add(k.Key - start, k.Value);
+						}
+					}
+
+					var last = samples.Last();
+					if (last.Key != (end-start))
+						samples.Add((end-start), last.Value);
+				}
 			}
 
 			public void Update(double time)
@@ -210,6 +234,22 @@ public void Update(double time)
 			}
 		}
 
+		public void CutRecording(double start, double end)
+		{
+			if (start == 0d && end >= lastRecordedTime)
+				return;
+
+			foreach (var d in data)
+			{
+				foreach (var track in d.Value.tracks)
+				{
+					track.CutTrack(start, end);
+				}
+			}
+
+			lastRecordedTime-=start-(lastRecordedTime-end);
+		}
+
 		public void StartRecording(double time)
 		{
 			startTime = time;