Add curve edge with arrow head rendering.
Rename edges renderers files in examples.
Fixing custom edge example.
Enchance edge renderer selection.
Fix issue with incorrect node type renderer.
Change edge type selection mechanism to default.
Fixing edge renerers path in examples.
Merge branch 'master' into HEAD

Conflicts:
	src/renderers/canvas/sigma.canvas.edges.arrow.js
	src/renderers/canvas/sigma.canvas.edges.curve.js
	src/renderers/canvas/sigma.canvas.edges.def.js
Minor changes for linter
Regenerated examples imports