feature/tp-triangle
This MR reverts previous work to pull triangle into Nektar++ and modify the source to better suit us. It proved that all the planned work on triangle never happened and the small amount that did may have reduced its robustness. For the sake of maintainability, this reverts triangle to being a thirdparty library taken directly from the unmodified source.
In addition a number of other issues have been found.
- Part of the high-order optimisation code was commented out (probably from debugging)
- Small optimisation to the octree code
- Fix progress bar in octree code for 2D meshes
- tAtArcLength function was not accurately calculated, this caused issues in very fine meshes