[FEATURE] Live heatmap renderer

Allows for live, dynamic heatmaps for point layers. Options include
specifying heatmap radius in pixels, mm or map units, choice of
color ramp, and a slider for selecting a tradeoff between render
speed and quality.
Add an invert checkbox for heatmap renderer
fix windows build
[processing] fix Field calculator algorthm (fix #11488)
[processing] redirect output from command line tools to Info tab (fix #5618)