20220328

First release:

• Displays multiple SVG files in the window
• Supports sizes: fixed (all typical icon sizes), window size, natural document size, and waterfall with multiple sizes
• Zoom in/out with Ctrl+mouse wheel, pan with scrollbars/keyboard/middle drag
• Grid display 'g'
• Backgrounds of transparent black (to keep the transparency), checkerboard, opaque white (for those solid color black/gray icons), opaque gray