Main chnages compare to 5.6.x version:

1. Add support of TProfile2Poly class
2. Add support of TGeoOverlap class, provide access from TGeoManager
3. Add support of TGeoHalfSpace for composites
4. Implement TF2 drawings update, see tutorials/graphics/anim.C
5. Improve windows handling in flex(ible) layout
6. Better position for text in TH2Poly drawings
7. Enable projections drawing also with TH2 lego plots
8. Use gStyle attributes to draw histogram title
9. Use requestAnimationFrame when do monitoring, improves performance
10. Support eve7 geometry viewer - render data generated in ROOT itself
11. Many adjustment with new TWebCanvas - interactivity,
attributes/position updates
12. Provide initial WebVR support (#176), thanks to Diego Marcos
(@dmarcos)
13. Upgrade three.js 86 -> 102, use SoftwareRenderer instead of
CanvasRenderer
14. Upgrade d3.js 4.4.4 -> 5.7.0
15. Use d3.js and three.js from npm when running with node.js
16. Fix - support clipping for tracks and points in geo painter
17. Fix - drawing of TGeoNode with finder
18. Fix - key press events processed only in active pad (ROOT-9128)
19. Fix - use X0/Y0 in xtru shape (#182), thanks to @altavir
20. Move most of ui5-specific code into ROOT repository, where it will
be maintained
21. Provide special widget for object inspector