Dolfin-adjoint

- Downstream fixes for turning on annotations
- Use Github to build webpage
- Add [Code of conduct](./CODE_OF_CONDUCT.md)
- Auto-publishing PYPI images added

- Remove firedrake_adjoint and pyadjoint from repo
- Simplify layout of code
- Use `src-layout``
- Use `pyproject.toml``

- Compatible with [ufl-legacy](https://github.com/FEniCS/ufl-legacy)

- Final release compatible with `ufl` pre [ufl-legacy](https://github.com/FEniCS/ufl-legacy)

- Support for FEniCS 2019.1.0
- Added function `taylor_to_dict`, which automatically computes shape derivatives and hessians without user input
- Added support for shape optimization. Supports "naive" shape optimization, computing shape derivatives with the ufl function `CoordinateDerivative`, as well as more advanced optimization, where only the boundary mesh nodes are the design variables. Demo can be found in `examples/stokes-shape-ad`.
- Added support for `FunctionAssigner`
- Reintroduced tape visualisation to graphviz dot files
- Added support for KrylovSolver and PETScKrylovSolver

- Support for FEniCS 2018.1.0