What's Changed
* README update by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/453
* Patch convective flux by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/460
* Patch stepsize steady state by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/464
* Avoid using UserExpression for Theta to mobile concentration conversion by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/466
* `Trap.materials` can only accept strings or `FESTIM.Material` by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/467
* Linear solver methods option by jhdark in https://github.com/RemDelaporteMathurin/FESTIM/pull/469
* Fix duplicate heat sources by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/474
* `Simulation.initialise()` resets `t` to zero by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/476
* Average surface derived quantity option by jhdark in https://github.com/RemDelaporteMathurin/FESTIM/pull/482
* `MinimumSurface` and `MaximumSurface` by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/483
* Refactoring `Simulation` by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/478
* New `SurfaceQuantity` and `VolumeQuantity` classes by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/475
* Temp from xdmf option by jhdark in https://github.com/RemDelaporteMathurin/FESTIM/pull/479
* Ability to export trap densities as an xdmf file by jhdark in https://github.com/RemDelaporteMathurin/FESTIM/pull/487
* Initialise `Stepsize.value` in `Simulation.initialise()` by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/486
* added __version__ attribute by RemDelaporteMathurin in https://github.com/RemDelaporteMathurin/FESTIM/pull/491