**As** an openproject user
**I** want speedy timelines in modern browsers
**so that** timelines render quicker

**Acceptance criteria**

- Begin of the insertion<s>UsersEnd of the insertion Begin of the deletion UsersEnd of the deletion of old IE versions are presented an adequate message informing about the Begin of the insertionincompatibilities.</s> (Subsumed in \#2613)End of the insertion Begin of the deletion incompatibilities.End of the deletion
- Timelines do not rely on IE8-specific performance-fixes, lending the timelines code more performance in modern browsers
- Timelines use SVG in all supported browsers and do not rely on VML fallbacks.