Cannot create png file, it seems that a space is needed

[metal3d]

Hi, I may have found a typo here

https://github.com/Arafatk/glot/blob/79d5219000f05727de933dbd5259b4dce6aacbc0/common.go#L179

If I'm not wrong:

outputFileCommand := "set output" + "'" + filename + "'" 

should be:

outputFileCommand := "set output" + " '" + filename + "'" 

That why I always use fmt.Sprintf :)

outputFileCommand := fmt.Sprintf("set output '%s'", filename)

I don't have tried, I'm using Jupyter and try to make an easy function to draw graphs, but at this time, with lgo project, i've got no output (and no error...) from SavePlot() function, investigating