Fix rev tools light dark mode

[mwieder]

Here's a possibility for fixing the multiple-stacks error you're getting from loading PowerTools.
I moved the background/foreground colorizing into your oxttools stack and dispatch the call from the home stack.

[PaulMcClernan]

The thing is the Tools stack I had always intended to swap out with something (hopefully) much better (see 'Tools redo' thread on the forums for example). I'd rather not put handlers for dealing with dark mode into IDE stacks, rather I think it should be handled in a separate library, one that we can then adjust for peculiarities in certain Linux themes or that can use a JS handler when run in a web browser environment to figure out if the user is in a dark theme / has light foreColor/dark backColor. We want a cross-platform 'darkMode'. Since this may involve evaluation of RGB triplets (because maybe the user is in a 'orange text on blue backColor' mode?), I think this should be put into an 'OXT color' library that covers the functionality of Quatram Color Library, tinyColor library, along with some handlers that I've created to RGB stuff and Read GIMP Color palettes.