Deleting Points and other features

Fortunately, the code required to delete a Point feature will also work for other types of geometries, so we don't need to implement separate DeletePointTool, DeleteLineTool, and DeletePolygonTool classes. Instead, we only need a generic DeleteTool. The following code implements this map tool:

class DeleteTool(QgsMapToolIdentify):
    def __init__(self, mapCanvas, layer):
        QgsMapToolIdentify.__init__(self, mapCanvas)
        self.setCursor(Qt.CrossCursor)
        self.layer   = layer
        self.feature = None

    def canvasPressEvent(self, event):
        found_features = self.identify(event.x(), event.y(),
                                       [self.layer],
                                       self.TopDownAll)
        if len(found_features) > 0:
            self.feature = found_features[0].mFeature
        else:
            self.feature = None

    def canvasReleaseEvent(self, event):
        found_features = self.identify(event.x(), event...