Separated the Spline Mathematical aspect from the Component into a new Spline class under Math. No angelscript or lua bindings as of yet as I'm unsure how to go about adding the templated class in a suitable manner.

Old Spline class has been renamed to SplinePath as is build using child nodes of its parent node. To facilitate the functionality a method has been added to Node to allows you to specify the index position of where to add the child Node as that impacts the curve.  DebugGeometry was added which shows the nodes that currently make up the SplinePath and the curve.

Added CScriptArray to PODVector convertor.
Refactored Spline to use Variant instead of being a template to allow easier implementation of Scripting APIs. Added additional type safety checks to ensure that the Variant underlying type is the same as existing elements.

Added Lua and Angelscript Bindings for SplinePath and Spline.

fixes #229
Changed SplinePath so that it is more flexible its logic is now separate from the scene hierarchy. Control Points are set and removed explicitly with the ability to define the order. Controlled Node is explicitly set so that the Move function affects that Node's WorldPosition.
Merge remote-tracking branch 'remotes/alexparlett/feature/spline'
Shuffling around of Spline to the Core library to make explicit that it depends on Variant (the dependency is no longer strict as Urho3D library is built as one piece, but is good to keep in mind to retain the Math library theoretically reusable outside Urho3D.)
Register DebugRenderer earlier in the AngelScript API registration for less special cases.