#359 Axis colors not preserved after export a graph

[Fellype]

If an axis of a graph has its color changed, the color of the line of the axis is not preserved when the graph is exported (as png, svg...). Instead of it, the exported image shows a black line.

Attached figures show the issue; one is a screenshot (color OK) and the other is an exported image (color not OK).
The attached project can be used to reproduce the issue - just try to export the graph and verify the resulting image.

Tested on Slackware 14.2, using SciDAVis 1.23 and 1.23.4.

[gbm]

Line color is preserved, but gets overwritten by a rectangular frame, as you
can check by exporting to SVG and editing the obtained file.
Attached patch solves the problem.

[Fellype]

Line color is preserved, but gets overwritten by a rectangular frame, as you can check by exporting to SVG and editing the obtained file.

I thought this could be the problem after try to export a graph using SciDAVis on Windows, but it was to late to tell you this.

Attached patch solves the problem.

Yes, it solves the problem. Thank you!