Syntax highlighting for the Verifast programming language.
Copy this package into your .vim directory, or use your vim plugin manager of choice.
Note that this package only detects .gh files as Verifast automatically- you don't necessarily want to apply Verifast syntax highlighting to every .c and .h file, after all. Just invoke :set filetype=verifast on your file of choice. (You can also add au BufRead,BufNewFile *.c set filetype=verifast to your .vimrc if you're bold.)