examples: error messages are not capitalized.

* examples/lock.lua: Don't capitalize error messages.
Discovered by 'make syntax-check'

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
maint: reorganise sources into subdirectories.

Rather than dump everything into the project root directory
indiscriminately, move extension modules into subdirectories
of a new 'ext/' subdirectory, Lua libraries into 'lib/'. And
adjust the build system to work with that layout.
* lua52compat.h: Move from here...
* ext/include/lua52compat.h: ...to here.
* local.mk (AM_CPPFLAGS): Add -I ext/include.
* lcurses.c, strlcpy.c, curses.lua: Move from here...
* ext/curses/curses.c, ext/curses/strlcpy.c, lib/curses.lua:
...to here.
* lposix.c, posix.lua: Move from here...
* ext/posix/posix.c, lib/posix.lua: ...to here.
* configure.ac (AM_INIT_AUTOMAKE): Add subdir-objects for future
compatibility with Automake 2.0.
(WANTEDLIBS, WANTEDLUA): Adjust paths.
* local.mk (std_cpath, std_path, EXTRA_LTLIBRARIES, lib_LTLIBRARIES)
(dist_data_DATA, dist_doc_DATA, EXTRA_DIST): Likewise.
* tree.lua: Move from here...
* examples/tree.lua: ...to here.
* make_lcurses_doc.pl, config.ld: Move from here...
* build-aux/make_lcurses_doc.pl, ext/posix/config.ld: ...to here,
and adjust for relative path changes.
* dummy.c: No longer used. Remove.
* build-aux/sanity-cfg.mk: Remove references to dummy.c.
Adjust for relative path changes.
* .gitignore: Update.

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