refactor: reformat and add LDocs to astr.lua.

* lib/zile/astr.lua: Reformat to match other object modules.
Return a table instead of perturbing the global namespace.
Add LDocs.
* lib/zile/estr.lua, lib/zile/buffer.lua: Adjust all callers.
* doc/config.ld (file): Add lib/zile/astr.lua.
* local.mk (dist_classes_DATA): Add lib/zile/astr.lua.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
doc: keep config.ld out of doc/ for LuaRocks docdir install.

* doc/config.ld: Move from here...
* build-aux/config.ld: ...to here.
* local.mk ($(dist_doc_DATA): Adjust.
* .gitignore: Update.
* NEWS: Update.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
doc: add the package name and version to html doc page titles.

* build-aux/config.ld: Move from here...
* build-aux/config.ld.in: ...to here.
(title, project): Substitute @VERSION@.
* .gitignore: Add build-aux/config.ld.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>