[BUG] Perspective Table number format breaks if first row has null value

Hopefully the underlying Perspective Table implementation will handle this in the future for columns with specified types. For now, this script transform does the trick:

	from java.lang import Float
	from com.inductiveautomation.ignition.common.util import DatasetBuilder
	
	if value is None:
		return value
	else:
		# Build new dataset with specified column types.
		colNames = ["Month 1", "Month 2", "Month 3"]
		colTypes = [Float, Float, Float]
		b = DatasetBuilder.newBuilder().colNames(colNames).colTypes(colTypes)
		# Copy original data into new dataset.
		for row in system.dataset.toPyDataSet(value):
			b.addRow(row[x] for x in range(len(row)))
		return b.build()