First cut at a loader.conf.d support

[kevans]

Summary

After we've finished processing all of the loader_conf_files at the root of the include tree, grab loader_conf_dirs and process any files within.

Currently nothing is off-limits; any files placed in one of these directories will be read.

[allanjude]

Reviewed By: allanjude

[rpokala]

stand/lua/config.lua

538

I'm having trouble parsing that pattern...?

[kevans]

stand/lua/config.lua

538

https://www.lua.org/manual/5.3/manual.html#6.4.1

A series of alphanumeric and punctuation characters, since that's also what we used for loader_conf_files. For punctuation, see ispunct(3)

[rpokala]

Code LGTM; suggestion for the manpage.

stand/defaults/loader.conf.5

259–261

While here, describe loader_conf_files too, since it doesn't have a description.

[imp]

stand/lua/config.lua

544

I think we want to restrict this to foo.conf, since emacs likes to leave behind foo.conf~ files.

[freqlabs]

stand/lua/config.lua

544

I'm on board with this, too. I wouldn't mind being able to move things to foo.conf.disabled or keep around foo.conf.old files, beyond just tolerating obnoxious editor defaults.

[allanjude]

stand/lua/config.lua

544

Yeah, making it loader.conf.d/*.conf is probably the safer thing to do.

[kevans]

stand/lua/config.lua

544

Sure, it's trivial to fix so I'll do so pre-commit. At some point I'd like to open up the option of .lua config files, too, but this is a similarly trivial addition later when I get to that point.