Final changes for glvis-4.3

[tzanio]

📆 Target release date: July 15, 2024

🟡 In Progress:

• [ ] #280
• [ ] #286

🔴 TODO:

• [ ] Command-line option to ensure minimal level of refinement to large meshes don't show as linear by default -- see #285 ← @tzanio
• [ ] Support for visualization of particle data?
• [ ] Switch from <key>A</key> to A in README.md? See this issue
• [ ] Update CHANGELOG ← @tzanio

🟤 Optional:

• [ ] https://github.com/GLVis/glvis/issues/272
• [ ] https://github.com/GLVis/glvis/issues/241
• [ ] https://github.com/GLVis/glvis/issues/268
• [ ] https://github.com/GLVis/glvis/issues/260
• [ ] https://github.com/GLVis/glvis/discussions/133

⚪ After the release:

• [ ] Update website, https://github.com/GLVis/web
• [ ] Update glvis-js and glvis.org/live
• [ ] https://github.com/GLVis/glvis-js/issues/7
• [ ] Update pyglvis

🟢 DONE:

• [x] Update version number from 4.2 to 4.3
• [x] #278 ← @v-dobrev will review

⚫ Postponed:

• https://github.com/GLVis/glvis/issues/274
• adaptive geometry refiner
• raytracing?!
• better vector graphics output
• improved testing with random keys
• #232
• #170
• #166