Nearest Peak Marker
class NearestPeakMarker(var traceIndex: Int, var name: String, var x: Double, var lowerYBound: Double? = null, var lowerXBoundMarker: String? = null, var upperXBoundMarker: String? = null, var referenceMarker: String? = null) : Overlay
Puts a marker on the trace at the nearest peak to a fixed x position