Extend the vendored GEMMI subset (v0.7.5) with the atomic-model, structure-factor,
bulk-solvent and map machinery so the whole thing builds as one static `gemmi`
library instead of a separate target:
- add the model/SF/map sources compiled into `gemmi`:
pdb, resinfo, polyheur, calculate, eig3, ccp4
- add the v0.7.5 headers these pull in (model.hpp, dencalc.hpp, sfcalc.hpp,
solmask.hpp, scaling.hpp, fourier.hpp, grid.hpp, ccp4.hpp, it92.hpp, ...)
plus third_party/pocketfft (FFT), half, tinydir
Only the low-level string/math/symmetry headers were present before; this makes
the vendored copy a complete, self-consistent gemmi that can read a PDB and do
density / structure-factor / map calculations.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>