updates reading of external models (adds nummaterial_velocity_file); updates Par_files and examples (in particular Marmousi_mesh_of_the_model/ and MODEL = marmousi)

[danielpeter]

No description provided.

[codecov]

Codecov Report

Attention: 353 lines in your changes are missing coverage. Please review.

Comparison is base (98741db) 54.29% compared to head (5d6c127) 54.49%.
Report is 14 commits behind head on devel.

Files	Patch %	Lines
src/specfem2D/read_external_model.f90	14.89%	160 Missing ⚠️
src/meshfem2D/read_external_mesh_files.F90	42.76%	91 Missing ⚠️
.../specfem2D/define_external_model_from_marmousi.f90	0.00%	45 Missing ⚠️
src/shared/read_parameter_file.F90	50.00%	25 Missing ⚠️
src/shared/read_material_table.f90	82.43%	13 Missing ⚠️
src/specfem2D/define_external_model.f90	0.00%	9 Missing ⚠️
src/specfem2D/setup_mesh.F90	96.95%	5 Missing ⚠️
src/meshfem2D/meshfem2D.F90	85.00%	3 Missing ⚠️
src/shared/read_value_parameters.f90	66.66%	1 Missing ⚠️
src/specfem2D/iterate_time_undoatt.F90	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            devel    #1202      +/-   ##
==========================================
+ Coverage   54.29%   54.49%   +0.19%     
==========================================
  Files         163      163              
  Lines       29681    30130     +449     
==========================================
+ Hits        16116    16420     +304     
- Misses      13565    13710     +145     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.