Knockout Plug

This is a remix of pabile's https://www.thingiverse.com/thing:3629334 in response to ivorbigun's forum topic https://www.thingiverse.com/groups/openscad/forums/general/topic:56370

The main body of the cap was replaced by a rotate_extrude() polygon and the slicerheight was adjusted to caplegthick*3 in order to accommodate for shorter cap leg thicknesses.