update Polygon to v1.4

update Polygon to version 1.4:

allow constructor to take vertex positions from initializer list,

allow a Polygon to be constructed from another polygon (constructor or assigned),

allow direct access to a Polygon's vertex,

allow ability to switch direction of vertices,

allow ability to set colour and texture co-ordinates for each vertex,

allow the usage of a texture,

adds ability to change the triangle limit,

adds automatic wireframe,

adds ability to get information such as its perimeter or area,

adds a point-in-polygon test,

adds local and global bounds,

adds ability to get "centroid" and "centre of mass" (different things),

allows the exporting of vertex positions or wireframe vertices,

allow holes.