Widget cartesian update line bugfix

[s-light]

fixes #61
and fixes misalignment of graph to axis.
there was a factor missing..

[FoamyGuy]

Thanks for working on this @s-light

[FoamyGuy]

Thanks for working on this @s-light. I have a few small requests but this is looking good to me for the most part.

Tested successfully on PyPortal 7.1.0-beta.3

[s-light]

@FoamyGuy i just questioned myself if it makes more sens to change the nameing to line_add() and lines_clear() or plot_add_line and plot_clear or graph_add_line and graph_clear
this way it feels a little bit better ordered....
what you are thinking?

[FoamyGuy]

@s-light I do like the idea of adding "plot" to the names to make it distinct from the axis lines. How about add_plot_line() and clear_plot_lines()?

[s-light]

so you prefer the action first naming?
(i personally prefer object subobject action naming... this also help for simple autocomplete - all the function/attribut names start with the object name the belong to...)
i am fine with this. :-)

[FoamyGuy]

LGTM

@s-light I do prefer action first naming. However I do see the upside you mention about autocomplete. I may be spoiled a bit in that regards. I think PyCharm autocomplete is good about showing options even if I enter them out of order so if I start typing something like my_plane.line I will still get add_plot_line and clear_plot_lines in the list of possible completions even though they don't begin with "line" like I started typing.