Show load as magnitude because the direction is already shown

[mhscott]

The plot_loads_2d function shows the proper direction of loads of negative magnitude, but the label still shows a negative value, implying a possible "double negative" interpretation, e.g., the -18.893 downward load shown below. My suggestion is to use abs() on the numbers after flipping the load arrows.

[mhscott]

@sewkokot Looks like a simple fix, but wanted to run it by you before making a PR

[sewkokot]

@mhscott Thank you, indeed the double negative interpretation can be misleading. I will fix it and release a new version, this week.

[sewkokot]

@mhscott Please update the package and let me know if it works.