Quad Improvements and T/C Member Bug Fixes

This release includes major program improvements for plates and important fixes for tension/compression-only members, but also includes breaking changes (detailed below).

• Changed quad elements from MITC4 formulation to DKMQ formulation. This greatly improves plate results at corners and increases the speed with which the plate's stiffness matrix is assembled. MITC4 element code has been retained as legacy code, but is no longer used by the program.
• Breaking Changes: Implemented snake-case for dictionary names (e.g. FEModel3D.Nodes is now FEModel3D.nodes). These changes were made to prepare Pynite for a v1.0 release that is consistent with the PEP8 style guide for python.
• Bug fix for tension/conpression-only member internal results. While global results were correct, member internal results were showing results from the first tension/compression only iteration.
• Member results arrays can now be customized to pick up user defined points. Member results arrays generate results much faster now too.

Rendering via `Pyvista` and Other Improvements

• Added rendering via Pyvista. This greatly simplified the rendering code and provided a fresh look to the rendereings. Renderings in jupyter are now interactive. Global axes are also now shown in rendereings. To use Pyvista instead of VTK, use the new Rendering library rather than the old Visualization library. Rendering via VTK directly is still available.
• Bug fix for member self-weight. The program was throwing exceptions instead of calculating member self-weight. Added a unit test to help prevent this issue from occuring again as code changes.
• Refactored material to be material_name in the code. The prior naming convention caused confusion which led to the self-weight bug.

Bug Fix for Phantom Reactions & Initializing `PhysMembers`

v0.0.93

• Fixed phantom reactions showing up at unsupported nodes. If there was a support defined at a node, the program was summing reactions for all directions at the node, rather than just the supported directions. This caused the program to report "extra" reaction directions at any supported node (if the user queried them). Element forces/stresses were not affected as this was a post-processing reaction summing issue. Reactions for supported directions were summed correctly, except in the case of nodes with both spring supports and other supports. Only unsupported directions, and nodes with both spring supports and other supports, were showing phantom reactions. This bug also caused statics checks to fail from time to time.
• Reorganized physical member code to match member code more consistently.

Member Self-Weight

Added a highly requested member self-weight calculation feature via FEModel3D.add_member_self_weight(). This only applies to members. This feature does not calculate self-weight for plate and quad elements.

Continued Migration to PyVista

Migrating visualizaton code from VTK to PyVista. PyVista greatly simplifies the rendering code, and simplifies adding new features to the renderings. This feature is only partially complete and partially functional.

Continued Migration to PyVista

Continued migrating visualizaton code from VTK to PyVista. PyVista greatly simplifies the rendering code, and simplifies adding new features to the renderings. This feature is only partially complete and partially functional.

Started Migrating Visualization from VTK to PyVista

Began migrating visualizaton code from VTK to PyVista. PyVista greatly simplifies the rendering code, and simplifies adding new features to the renderings. This feature is only partially complete and partially functional.

Updates to `PhysMember` Code

General housekeeping for PhysMember code. to bring it into alignment with the Member code.

P-little-delta Improvements

v0.0.87

Update for v0.0.87

P-little-delta Improvements

v0.0.86

Sign convention update