make asymptote show configurable

[kcrisman]

From  this ask.sagemath.org question:

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See the  source code (this is version 4.8).

    pole_options = {}
    pole_options['linestyle'] = '--'
    pole_options['thickness'] = 1
    pole_options['rgbcolor'] = '#ccc'

Unfortunately, I think that the only way to change these options right now is to change it in your actual plot file! You can go into your Sage installation's devel/sage/sage/plot/plot.py file and search for these lines, and then just change them, start Sage with the command line option sage -br and hopefully a thicker line would be available.

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Well, these should be configurable! So this ticket is about making these accessible to all viewers.