Tooltip improvements

[techniq]

• [x] Use portal
  • Will fix stacking context issues (z-index set on parent, etc)
• [ ] Allow keeping tooltip open (copy values, etc)
  • Mouseover directly into tooltip (what if there is a gap between anchorEl and popoverEl). Add small time threshold?
  • Click to keep open (what about a button?)
• [ ] Crossfade location between instances
• [ ] Animate and tilt