WIP: Misc partial things...
Progress reported integrated into all renderers.
Interruptable rendering (w/status bar).
Faster (but restricted) version of glyph-paralle rendering.  Assumes that all glyphs exactly the shape of their bounding boxes and uniform in their aggregator function.  Can only do single-glyph aggregagors (though aggregator reducers weaken this restriction with creative phrasing).
Demo app running for the first time.
Fixed zoom-fit breaks transfer-only render in demo app.
Moved the main panel to the components sub-branch.