Path Library Improvement

Inkscape relies on two libraries for its geometry related operations. One is lib2geom which was designed specially for Inkscape and the other is livarot, a library written in 2003 that has some unique features which lib2geom doesn't have. Features such as: path simplification, path flattening, line scanning (flowing text), path offset/inset, boolean operations and some modes of tweak tool. While livarot is functionally good, it's quite outdated. It was written in 2003, it's extremely hard to understand it or maintain it. The goal of this project is to implement all of these features either in lib2geom or outside it while using lib2geom's features as much as possible.