Allow examples and test-suite to be built out of source tree

- Examples/Makefile.in rules use SRCDIR as the relative source directory

- ./config.status replicates Examples/ source directory tree in build
  directory, and copies each Makefile to build directory, prefixed with
  a header which sets SRCDIR to source directory

- Examples/test-suite/.../Makefile.in set SRCDIR from Autoconf-set srcdir

- Examples/test-suite/errors/Makefile.in needs to filter out source
  directory from SWIG error messages

- Lua: embedded interpreters are passed location of run-time test

- Python: copy run-time scripts to build directory because of 2to3
  conversion; import_packages example copies __init__.py from source
  directory; test-suite sets SCRIPTDIR to location of run-time tests

- Javascript: binding.gyp renamed to binding.gyp.in so that $srcdir
  can be substituted with SRCDIR; removed './' from require() statements
  so that NODE_PATH can be used to point Node.js to build directory

Examples/python/import_packages/Makefile

@@ -5,7 +5,7 @@ LIBS       =
 PY3        =
 
 import_packages_subdirs = \
-  same_modnames1 \
+	same_modnames1 \
 	same_modnames2 \
 	from_init1 \
 	from_init2 \
@@ -14,8 +14,13 @@ import_packages_subdirs = \
 	relativeimport1
 
 check: build
+	if test "x$(SRCDIR)" != x; then \
+		for file in `cd $(SRCDIR) && find . -type f -name __init__.py`; do \
+			cp "${SRCDIR}$$file" "$$file" || exit 1; \
+		done; \
+	fi; \
 	for s in $(import_packages_subdirs); do \
-	  (cd $$s && $(MAKE) check); \
+		(cd $$s && $(MAKE) check); \
 	done
 
 build:
@@ -29,7 +34,7 @@ static:
 	done
 
 clean:
-	$(MAKE) -f $(TOP)/Makefile python_clean
+	$(MAKE) -f $(TOP)/Makefile SRCDIR='$(SRCDIR)' python_clean
 	for s in $(import_packages_subdirs); do \
 		(cd $$s && $(MAKE) clean); \
 	done