Standalone enter/leave animations

[denisinvader]

This should affect only arrays and objects animations.

For now, enter and leave keys are just added or removed from target eg. It would be nice to add enterValue and leaveValue (names are just for reference) and animate enter keys from enterValue to provided values and leave keys to leaveValue.

It will allow avoiding usage of <transition-group /> and animation parameters duplication.

Example

enterValue = leaveValue = 0

State 1:

{ x: 10, y: 15 }

State 2:

{ x: 20, z: 10 }

target (slot scope) updates:

• x animated from 10 to 20;
• y animated from 15 to 0, when the animation is finished, this key removes from target;
• z added to target then animated from 0 to 10.