Underworld

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New features:
* New 'long' type swarm variable.
* User provided post-solve callback functionality added.

Enhancements:
* Speed up (minimum 5x) for SwarmVariable reload.
* Petsc-3.8 compatible.
* Non root dockerfile now.

Documentation:
* Viscoelastic tutorial, see ./docs/tutorials/
* Update raijin and magnus build instructions.

API Changes:
* New interface for a MeshVariable, mesh.add_variable().
* New interface to Integrate, mesh.integrate().

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* Updating release to the correct version of lavavu

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Documentation:
* Darcy flow models.
* New NCI Raijin build recipe.
* Many new models and tutorials.
* Cheatsheet added.

Enhancements:
* Docker usage no longer requires tokens.
* KSP convergence status now captured in python interface.
* `solve()` method now displays warnings for floating point over/underruns.
* Many general enhancements to visualisation.

New Features:
* New features for `min_max` function.
* solHA added.

API Changes:
* `min_max` function no longer accepts vector functions
by default, with instead a fn_norm function having to
be provided by the user.
* Neumann condition now takes `indexSetsPerDof` parameter instead of `nodeIndexSet`.

Bug fixes:
* Catch out fortran ordered numpy arrays when using `evaluate()` method.
* Parallel isosurface visualisation fixed.
* Corrected sampling for FieldSampler visualisation object.

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Enhancements:
* Improved swarm reload times for parallel simulations.
* Efficiency improvements for large proc count (>128) parallel simulations.
* Faster algorithms for swarms with deformed mesh.
* Many updates to visualisation routines.
* Compressible Stokes general improvements.
* New example models and analytic tests.
* Addressed numerous memory leaks (some minor ones still exist).
* Improved error handling, documentation & testing.


New features:
* User provided pre-solve callback function.
* Updated or new vis objects: Isosurfaces, contours, discrete colourmap.

API Changes:
* Neumann condition change in user provided stress function.

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Bug fixes:
* Critical bug fixed where retrieving symmetric tensor in 3d returned 2d result.

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Documentation
* Updates to make api documentation available via read the docs: http://underworld2.readthedocs.io/