[luatex] Finding user-specific Lua binary packages

[Dirk Laurie]

I'm using luatex as installed by Ubuntu 14.04 LTS.

A Lua script loaded by `luatex` inside`\directlua' does not consult
package.path and package.cpath. It examines package.preload, and
then tries the kpse lua searcher and the kpse C searcher.

`kpsepath lua` and `kpsepath so` are not valid pathtypes, but I have
discovered that I can put Lua scripts in $HOME/texmf/scripts/lua and
`require` inside `\directlua` will find them with no need to `texhash`.

However, packages provided as shared objects are not found if put
there, and I have not discovered where in $HOME/texmf I can put them.
The manual says they are looked for in

    CLUAINPUTS=.:$SELFAUTOLOC/lib/{$progname,$engine,}/lua//

but this path seems not to provide for $HOME/texmf. I could put
a symbolic link to the .so files in `.` every time, but that really defeats
the purpose of kpse.