vfs: use propertycache for open The current open method is currently behaving like a property cache. We use our utility decorator to make this explicit.

help: add example of '[templates]' usage V2: - move from shortest() with minlength 8 to minlength 4 - mention [templates] in config.txt - better describe the difference between [templatealias] and [templates] V3: - choose a better example template

check-commit: allow underbars in cffi_-prefix function names It seems reasonable to give cffi functions slightly more verbose names in some circumstances, given the way they interface with C.