- Implemented more BrushGeometry methods, mostly for computing brush vertices.
- Implemented test cases.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>
- Fixed and adapted brush geometry computation.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>
- Improved tests for building the brush geometry.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>