New example WebGl-Geometry-Text-2 uses new triangulation PnlTri.js V1.0

As suggested in #4920 here is a new example "WebGl-Geometry-Text-2" which uses a new triangulation "PnlTri.js V1.0". This is an implementation of the near-linear triangulation method of Raimund Seidel creating a trapezoidation (visibility map) of a polygon first. For simple polygons without holes an easy ear-clipping mechanism is used derived from the one presently included in Three.js . Thus this triangulation should always be at least as fast as the present one and in complex cases significantly faster.