Feynman-diagram library, made for RustFig (original work, MIT OR Apache-2.0).

Parts for Feynman diagrams: straight fermion and anti-fermion lines (arrow in
the middle), scalar (dashed), ghost (dotted), photon (wavy), W/Z boson (heavy
wavy), gluon (curly) and graviton lines, each horizontal (1 inch; turn them with xfig's Rotate
modes), half-circle arcs for loops, vertex dot, hatched and grey blobs,
momentum arrows, and four complete example diagrams (example_*.fig).

Every line part ends on the 1/4-inch grid: with grid snapping on, join parts
end to end. Labels are LaTeX text with the TeX flag: type $e^-$ with the Text mode.

The files are written by `cargo xtask libraries` (xtask/src/libraries.rs);
change the generator, not the files.
