HistogramWidget plot title not white in dark theme

[dstansby]

See the title here:

[dstansby]

I think this is general across all plots

[K-Meech]

Just to add that for me all the axis labels are black for the histogram (including numbers on both axes). This is with a new install on Windows via the Napari UI Plugins > Install / Uninstall Plugins...

[Chris-N-K]

This should be fixed with the merge of #237

[dstansby]

Amazing!