Felupe

Added
- Add `project(mean=True)` to project cell mean-values to mesh-points. Now `project()` supports Triangles and Tetrahedrons.
- Add `RegionBoundary.mesh_faces()` for a mesh with face-cells on the selected boundary of a region.
- Add pseudo-elastic material `OgdenRoxburgh()` which may be used with `SolidBodyNearlyIncompressible()`.
- Add `umat = UserMaterial(stress, elasticity, nstatevars=0, **kwargs)` with user-defined functions for the (first Piola-Kirchhoff) stress tensor `P, statevars_new = umat.gradient([F, statevars], **kwargs)` and the according fourth-order elasticity tensor `A = umat.hessian([F, statevars], **kwargs)` based on the deformation gradient.
- Add `UserMaterialStrain()` for small-strain based user-defined material formulations with an umat-interface suitable for elastic-plastic frameworks.
- Add `LinearElasticPlasticIsotropicHardening()` which is based on `UserMaterialStrain()` and `constitution.linear_elastic_plastic_isotropic_hardening()`.
- Add new math helpers `math.ravel()` and `math.reshape()`.
- Add optional axis argument on which the norm is evaluated `math.norm(axis=None)`.

Changed
- Unify material definition with methods for the stress `P, statevars_new = umat.gradient([F, statevars])` and the elasticity tensor `A = umat.hessian([F, statevars])`. This breaks support for materials defined by matadi<=0.1.10.
- Do not broadcast the (constant) elasticity tensor for linear-elastic materials as `einsumt>=0.9.3` supports broadcasting along the parallel-executed dimension.
- Change not-updating attribute of `FieldContainer(fields).values` to a method `FieldContainer(fields).values()` which returns the current field values.

Removed
- Remove unused `SolidBodyTensor()` and `SolidBodyTensorNearlyIncompressible()`.
- Remove unused `region` argument of `LinearElastic().hessian()`.

Fixed
- Fix volume evaluation of (nearly) incompressible solids for axisymmetric fields.

Added
- Add optional pre-compression to shear-loadcase `dof.shear(compression=0.0)`.
- Add `MeshContainer` and string-representation for `Mesh` objects.
- Add a mesh-reader using meshio `mesh.read(filename, ...)`.
- Add `SolidBodyNearlyIncompressible(umat, field, bulk)` for (nearly) incompressible solids and a given (distortional-part only) constitutive material formulation. This is a pure displacement-based alternative to the three-field-formulation technique.

Changed
- Support an optional user-defined meshio-object in `Job().evaluate(mesh=None, filename="result.xdmf")`.
- Support a distortional-part only Neo-Hookean material formulation with no bulk modulus defined `NeoHooke(mu=1.0)`.

Fixed
- Fix missing `ArbitraryOrderLagrangeElement.points` attribute.
- Fix ignored mask `only_surface=True` for `RegionBoundary().mesh.cells_faces`.
- Set default pressure to zero in `SolidBodyPressure()`.
- Take the mesh from the global `x0`-field if `x0` is passed to `job.evaluate(x0=...)`.
- Fix missing update of global field `x0` in `job.evaluate(x0)` after each completed substep.

Added
- Add `xscale` and `yscale` arguments to `CharacteristicCurve.plot()`.
- Add `mesh.Grid(*xi)` as generalized line, rectangle or cube with custom linspaces.
- Add `mesh.concatenate(meshes)` to join a sequence of meshes with identical cell types.
- Add `x0` argument to `Job.evaluate(x0=field)`.
- Add `mask` argument to `mesh.runouts(mask=slice(None))`.
- Add `callback(stepnumber, substepnumber, substep)` argument to `CharacteristicCurve()` (like in `Job()`).
- Add an on-the-fly XDMF writer for a job (via meshio) `Job.evaluate(filename="result.xdmf")` with the possibility to add optional `point_data` and `cell_data` dicts.

Changed
- Remove Warning if `einsumt` requirement is not found (switch to numpy without any warnings).
- Requires Python 3.7+.

Fixed
- Fix ignored axis argument of `mesh.revolve(axis=1)`.
- Fix missing `ArbitraryOrderLagrangeElement.points` attribute.

Changed
- Enhance `Boundary`: Select Points by value in addition to a callable (`fx=lambda x: x == 0` is equivalent to `fx=0`), also add `mode="and"` and `mode="or"` argument.
- Support line elements within the revolution function `mesh.revolve()`.
- Import previously hidden functions `fun_items()` and `jac_items()` as `tools.fun()` and `tools.jac()`, respectively (useful for numeric continuation).
- Add step- and substep-numbers as arguments to the `callback(stepnumber, substepnumber, substep)`-function of a `Job`.

Added
- Add `SolidBodyGravity` for body forces acting on a solid body.
- Support list of linked fields in Newton-Rhapson solver `newtonrhapson(fields=[field_1, field_2])`.
- Automatic init of state variables in `SolidBodyTensor`.
- Add `mesh.runouts()` for the creation of runouts of rubber-blocks of rubber-metal structures.
- Add `FieldPlaneStrain` which is a 2d-field and returns gradients of shape `(3, 3)` (for plane strain problems with 3d user materials).
- Add `PointLoad` for the creation of external force vectors.
- Add `Step` with a generator for substeps, `Job` and `CharacteristicCurve`.

Changed
- Move `MultiPointConstraint` to mechanics module and unify handling with `SolidBody`.
- Rename `bodies` argument of Newton-Rhapson solver to `items` (now supports MPC).
- Return partitioned system as dict from loadcases `loadcase=dict(dof0=dof0, dof1=dof1, ext0=ext0)`.
- Check function residuals norm in `newtonrhapson()` instead of incremental field-values norm.

Fixed
- Fix assembled vectors and results of `SolidBodyPressure` for initially defined pressure values.
- Fix `verbose=0` option of `newtonrhapson()`.
- Fix wrong assembly of axisymmetric mixed-fields due to introduced plane strain field-trimming.