Crosshair plugin - out of graph bounds selection filter

[n-gist]

When the graph is zoomed in, crosshair can select points out of view area, drawing lines off graph. Below is example where the area on the left is caused by axisLabelWidth, so it is inside crosshair drawing canvas.

The same happens on the right side when using rightGap. Filtered by checking selectedPoint.x to be in [0,1]