Enable the line curve in the line annotation

[stockiNail]

This PR is enabling the line curve representation by the line annotation.

Option	Type	Default	Description
curve	boolean	false	if true, the line will be drawn as a curve
controlPoint	string - number- {x: string - number, y: string - number}	{y:'-50%'}	Distance (in px or percentage of the distance between the start and end point) from the center

It uses quadratic curve and Path2D.

TODO

• [x] review control point calculation
• [x] test cases
• [x] types
• [x] documentation
• [x] sample

[kurkle]

@stockiNail I'm not merging these, so you can decide the order you want to go.