added engine.timing.isFixed option
added Engine.render, moved respective engine event triggers into Engine.update and Engine.render
changed correction to now be optional in Engine.update (defaults to 1)
fixed: changed correction to now be optional in Engine.update (defaults to 1)
changed engine.timing.timestamp to be simulation based rather than wall-clock based
fixed Vertices.centre calculation
removed body.render.path
added Vertices.chamfer (for rounding corners)
added Demo.rounded
added Mouse.setScale, Mouse.setPosition, mouse.absolute
fixed Mouse.setScale and Mouse.setOffset
added mouse.wheelDelta
added scale support to Render
added scaling to Demo.views