Creates a line from two points. When the end points are `CAP_ROUND`, you can use `$fa`, `$fs` or `$fn` to controll the `circle` module used internally.
-`p1Style` : The end-cap style of the point `p1`. The value must be `"CAP_BUTT"`, `"CAP_SQUARE"` or `"CAP_ROUND"`. The default value is `"CAP_SQUARE"`.
-`p2Style` : The end-cap style of the point `p2`. The value must be `"CAP_BUTT"`, `"CAP_SQUARE"` or `"CAP_ROUND"`. The default value is `"CAP_SQUARE"`.