configury: use static list of SOURCES instead of $(filter)ing.

* Makefile.am (SOURCES): Remove the GNU Make extensions used to
dynamically build the list, and just list each file statically.
bugfix: make sure getopt.opt is updated in the module table.

Fix a bug preventing visibility of getopt.opt after port to Lua
5.2 style modues.
* src/getopt.lua (M): Add opt table. Move declaration above...
(processArgs): ...here, and update M.opt instead of undeclared
opt variable.
Merge other public entry points into M table before returning.
specl: new specification testing framework.

* specs/lib/specl.lua: New file for specification testing.
* specs/specl: New file.  Command line wrapper for specl.lua.
* specs/table_ext_spec.lua: New file. Specl tests for
src/table_ext.lua.
* Makefile.am (src_spec, lib_spec): Lua search path strings for
directories in the source tree.
(LUA_ENV): Adjust.
(SPEC_ENV): New macro. Set Lua environment for calling specl.
(SPECS): New macro.  A list of specs/*_spec.lua files.
(EXTRA_DIST): Add new specification testing files.
(check-local): Hook the specl tests into the Automake test
framework.
maint: update table_ext.lua to use Lua 5.2 style modules.

* src/table_ext.lua: Save unextended package table, returning that
after injecting stdlib extensions.
Declare everything locally.
(M): Public interface.
specs: specify return of the unextended module from table_ext.

* specs/table_ext_spec.lua (context when requiring the module): A
few new specifications for requiring table_ext.
maint: update package_ext to use Lua 5.2 style modules.

* src/package_ext.lua: Save unextended package table, returning
that after injecting stdlib extensions.
specs: add specl specification for package_ext module.

* specs/package_ext_spec.lua: New file. Specl specs for
package_ext.
* Makefile.am (SPECS): Add specs/package_ext_spec.lua.