A lyrics and chords formatting program

Changes for 6.030 - 2023-09-18

• !Highlights
• [ABC](chordpro.org/chordpro/directiv…) and [Lilypond](chordpro.org/chordpro/directiv…) embedding now use SVG (vector graphics) instead of pixmap images. This is very crisp at all sizes, and greatly reduces the size of the resultant PDF document.
• The ChordPro GUI (`wxchordpro`) has been extended with a Tasks menu that can be used to quickly select presets for a specific task. For example, to produce a PDF with only lyrics, or with keyboard diagrams instead of string diagrams. User presets can be added by placing small config files in a `tasks` folder under the `CHORDPRO_LIB`.
• !ChordPro functionality
• Directives and config to change the [chorus appearance](chordpro.org/chordpro/directiv…).
• Add support for SVG images. Allow `pdf.fonts.XXX` as fonts in SVG.
• Handle ABC and Lilypond embedding via SVG images. No more need for ImageMagick. Add 'staffsep' option for ABC embedding.
• Add 'omit' to delegates config.
• Infer chord inversions for keyboard.
• Use SVGPDF text callback to substitute missing flat/sharp glyphs.
• Trap missing font sizes (should not happen).
• !Breaking changes
• The image scale strategy was changed to be more intuitive. See [this forum message](groups.io/g/ChordPro/message/1…) for details.
• !Experimental
• A primitive but effective docker based web app.
• !BugFixes
• Fix issue #297.
• Fix issue #298.
• Fix issue message/1780.
• Fix issue #300.
• Fix issue #301.
• Fix issue #309.
• Fix issue #311.