[TIMOB-12945] Specification: Flesh out the v2 polynomial layout specification

Need to implement the spec for the v2 polynomial layout. The v1 spec is at https://wiki.appcelerator.org/display/spe/UI+Polynomial+Layout+Algorithm. v2 will expand by introducing the concept of a bounding box that controls exist in, and then layouts position bounding boxes. This means there will be two sets of coefficients: a common, generic set on the control itself which will most likely be identical to the v1 composite spec, and then layout specific coefficients for the bounding box. This two level pass should allow us to perform a variety of optimizations, including breaking out some of the conditional statements in the core of the current algorithm