Creates a polyline from a list of `x`, `y` coordinates. When the end points are `CAP_ROUND`, you can use `$fa`, `$fs` or `$fn` to controll the circle module used internally.
-`startingStyle` : The end-cap style of the starting point. The value must be `"CAP_BUTT"`, `"CAP_SQUARE"` or `"CAP_ROUND"`. The default value is `"CAP_SQUARE"`.
-`endingStyle` : The end-cap style of the ending point. The value must be `"CAP_BUTT"`, `"CAP_SQUARE"` or `"CAP_ROUND"`. The default value is `"CAP_SQUARE"`.
-`$fa`, `$fs`, `$fn` : Check [the circle module](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_the_2D_Subsystem#circle) for more details. The final fragments of a circle will be a multiple of 4 to fit edges if possible.