New features

[Illya_Voronov1]

Would be nice to have next features in future:

1. toggle action for width and height to switch values
2. ability to narrow down sides for rectangl while having rounded corners (img 2)
3. more options for line cap (img 3)
4. gif format export
5. repeat grid tool
6. 3D rotation tool
7. stroke customization for polygon & star tools

Thanks for all hard work