Font Overview tasks

[justvanrossum]

Followups for #1849, fixing #102.

The task items are not necessarily ordered by priority.

• [font overview] Add selectable and customizable "template" char sets #1937
• [font overview] Use URL fragment to read/write UI settings #1914
• Design/define what categories we'd like the cell view to use, and how customizable that should be
• [font overview] Implement a form of glyph/character grouping #1903
• Something with unicode properties: https://www.npmjs.com/package/unicode-properties
• [font overview] Improve shift-click behavior and implement shift-arrow-key #1898
• [font overview] Arrow key behavior #1897
• [font overview] Make side bar resizable #1945
• [font overview] Implement glyph deletion #2354
• [font overview] Implement glyph copy/paste #2356
• Add a context menu (Implemented by [font overview] Implement "delete glyphs" and a few more things #2355)
• Add UI to make cell size customizable (menu bar menu items, under "View") Done in Refactoring top bar / menu bar #1925
• [glyph-cell] distinguish between "loading" and "glyph not present in font"
• [glyph-cell] add glyph info tooltip #2767
• [font overview] Menu bar for font overview #1845
• Implement click-drag select multiple glyphs (Implemented by [font overview] Glyph cell view drag #2350)
• [related-glyphs] "Related Glyphs" should use glyph-cell-view #1887
• [font overview] Add Unicode Block as group-by category #1909
• [font overview] improve grouping of unencoded glyphs #1912
• [font overview / glyph sets] Add a default glyph set to "project glyph sets", so a new project shows something #1944
• [font overview / glyph sets] Finish glyphset parser (read tsv/csv, text + glyph names) #1968
• [font overview / glyph sets] Add URL filter that turns Google Docs and Sheets links into raw txt / csv links. GH links -> jsdelivr #1969
• [font overview / glyph sets] Add in-line help text in "Add glyph set" dialog
• [font overview / glyph sets] Refactoring glyphset logic to GlyphOrganizer
• [glyph-cell-view] Improve arrow up/down so it won't skip short cell lines (Fixed by [font overview] Fix arrow key up/down behavior #2351)
• [font overview] Show placeholder text if no glyphs are visible #1946
• [font overview / glyph sets] Implement undo/redo for glyphset adding/deleting/editing
• [font overview] Add location sliders #1948
• [font overview] Make sources popup respond to changes in sources #1974
• [font overview] Glyph cells should respond to changes in font sources, customData #1975

More tasks may be added

All issues shall be prefixed with [font overview], or more specific, for example [glyph-cell]