Improve examples for TFT

[hverhelst]

Add benchmarks for the paper

Verhelst, H. M., Möller, M., & Den Besten, J. H. (2025). A wrinkling model for general hyperelastic materials based on tension field theory. Computer Methods in Applied Mechanics and Engineering, 441, 117955.

[Copilot]

Pull Request Overview

This PR enhances the TFT examples by adding benchmark executables, refining mass‐assembly output, and improving XML boundary‐condition formatting.

• Introduced two new benchmark programs for cylinder and pillow TFT cases.
• Updated mass assembly in the static_shell_XML.cpp solver to use direct RHS output.
• Expanded single‐line <Function> tags in several XML PDE files to explicit <c> entries.

Reviewed Changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
unittests/gsStaticSolver_test.cpp	Removed stray whitespace
src/gsStaticSolvers/gsStaticNewton.hpp	Initialized m_dofs from system matrix row count
src/gsStaticSolvers/gsStaticDR.hpp	Set m_residualIni on first residual computation
solvers/static_shell_XML.cpp	Switched to assembleMass(true) and updated output path
filedata/pde/*.xml	Reformatted zero‐value <Function> tags into <c> blocks
benchmarks/benchmark_cylinder_DC.cpp	Added full wrinkling benchmark implementation
benchmarks/benchmark_Pillow.cpp	Added pillow benchmark tweaks and new command‐line flags

Comments suppressed due to low confidence (2)

benchmarks/benchmark_cylinder_DC.cpp:2

• The @file comment references benchmark_TensionWrinkling.cpp but the file is named benchmark_cylinder_DC.cpp. Please update the comment to match the file name for clarity.

/** @file benchmark_TensionWrinkling.cpp

solvers/static_shell_XML.cpp:332

• The variable sep is not defined in this scope, which will cause a compilation error. Consider replacing it with a literal path separator (e.g., "/" or gsFileManager::separator()) or ensure sep is defined.

      gsWrite(mp_def,dirname + sep + "deformed");