Basic triangulation, Polygon visual, example and PolygonData

Refactored PolygonVisual to use PolygonData, added conversion from line data to line strip data

Added primitive setting option to visual, modified line visual and polygon visual, scraped line to line strip data conversion

Added border.mode and remove primitive setter in visual

Added EllipseVisual, example, tweaked PolygonVisual

Added center to ellipse

Added incomplete triangulation, PolygonVisual, PolygonData, EllipseVisual
Moved geometry to vispy.util
Made all files except geometry.triangulation PEP8 compliant
Made triangulation PEP8 compliant
Added transform setter in Polygon and tested in Ellipse example
Modified transform setter in PolygonVisual
Modified transform setter in polygonvisual
Merge pull request #275 from mssurajkaiga/visuals_and_geometry

WIP: Visuals and geometry