Polygon - update to v1.4

[Hapaxia]

update Polygon to v1.4

adds:

• vertex color, and tex-coords
• bounds (local and global)
• texture (used by tex-coords if set, ignored if not set; always ignored by wireframe)
• ability to provide points in a reversed direction (i.e. clockwise for outer and anti-clockwise for holes - instead of anti-clockwise for outer and clockwise for holes)
• ability to get perimeter of polygon (length of all edges; include hole edges)
• ability to get area of polygon (after triangulation)
• ability to get if point is inside polygon (after triangulation)
• ability to get centroid (average of all outer's points; doesn't include hole vertices)
• ability to get centre of mass (actual centre of mass; based on triangles' areas)
• ability to get and set (existing) hole start indices/number of holes
• export vertex positions (the actual vertices forming the polygon boundary, in order)
• export vertex positions for only the outer boundary (does not include hole vertices)
• export vertex positions for only the given hole (vertices for the hole)
• export wireframe position (in pairs for each separate line)
• constructors (from other Polygon or initializer list of positions) and operator= (from other Polygon)
• operator[] to provide direct access to vertices (no validity checking). note that these are the vertices of the polygon "blueprint" - the thing you provide - not the actual vertices used to draw the shape.

also fixed:

• draw() signature: removed "virtual", added "override final" (just code-style update)
• now tests exception flag before throwing error in trangulation; also moved exception flag into cpp. note that this flag is always set to true.