update CMesh for 1D (preliminary support)
update Region, Domain and FEDomain for 1D, update orient_elements()

- update geometry_data
update .gitignore
update diffusion and Navier-Stokes terms for 1D

- update Term.geometries
update tests/test_term_call_modes.py for 1D
update C implementation of hyperelasticity for 1D
update VTKMeshIO.write() for 1D
add 1D reference elements meshes (1_2_1.mesh, 1_2_2.mesh)
new examples/diffusion/laplace_1d.py + test
update SDLinearElasticTerm for 1D
support custom material parameter values in tests/test_term_call_modes.py

- update make_term_args()
- add custom value for 'dw_s_dot_grad_i_s' in Test._test_single_term()
update Region for no Region.edges in 1D
update examples/diffusion/laplace_1d.py for variable coefficient

- update docstring, ebcs, mesh_hook()
- new get_coef(), functions
add custom view for laplace_1d.py example to script/gen_gallery.py
update GenericFileSource.get_bounding_box(), .create_dataset() for 1D
Merge branch '1d'
update AUTHORS
script/gen_gallery.py: simplify section titles, generate better labels
docs: update doc/index.rst for 1D and new gallery labels
docs: sync doc/introduction.rst with doc/index.rst