Implement KisAlgebra2D::mapToRect()

This commit adds KisAlgebra2D::mapToRect(), which is copied from a portion of the following commit:
commit 9fbdfcf436580117cb8b82853a0b79486e3145bb
Author: Dmitry Kazakov <dimula73@gmail.com>
Date: Mon Nov 14 12:04:07 2016 +0300

Implement a skeleton for relative clip path rendering test