Added the ability to disable drawing lines between points (for a scatter-like chart).

Also, constant lines are now drawn over the data.  I'm not sure this is appropriate either, but in the case of the NucTrans data, this definitely works better.  Perhaps this concept needs to be abstracted a bit more, but for now, this will do.

Plot.py

@@ -115,6 +115,8 @@ class Plot( SVG.Graph ):
 	"""Show a small circle on the graph where the line
 	goes from one point to the next."""
 	show_data_points = True
+	"Indicate whether the lines should be drawn between points"
+	draw_lines_between_points = True
 	"Set the minimum value of the X axis"
 	min_x_value = None
 	"Set the minimum value of the Y axis"
@@ -228,7 +230,6 @@ class Plot( SVG.Graph ):
 
 	def draw_data( self ):
 		self.load_transform_parameters()
-		self._draw_constant_lines( )
 		for line, data in izip( count(1), self.data ):
 			x_start, y_start = self.transform_output_coordinates(
 				( data['data'][self.x_data_index][0],
@@ -243,11 +244,13 @@ class Plot( SVG.Graph ):
 					'd': 'M%(x_start)f %(graph_height)f %(lpath)s V%(graph_height)f Z' % vars(),
 					'class': 'fill%(line)d' % vars() } )
 				self.graph.appendChild( path )
+			if self.draw_lines_between_points:
 				path = self._create_element( 'path', {
 					'd': 'M%(x_start)f %(y_start)f %(lpath)s' % vars(),
 					'class': 'line%(line)d' % vars() } )
 				self.graph.appendChild( path )
 			self.draw_data_points( line, data_points, graph_points )
+		self._draw_constant_lines( )
 		del self.__transform_parameters
 
 	def add_constant_line( self, value, label = None, style = None ):