[Feature Request] Add dashed lines

[cavemanloverboy]

I recently tried to plot two lines of O(1.0) that were overlapping to within 1e-11. I thought it'd be great to plot one of them as a dashed line but found no feature to do so. Plotting each point as a dot with Circle worked okay, but would be great to have an enum or bool that is passed into LineSeries to generate dashed lines.

[facorread]

Duplicate of #321

[cavemanloverboy]

closing due to duplicate