Fix various distro issues.
	* doc/manual/Makefile.am (SRC_FILES): Add the missing bits.
	* doc/doc.mk: Fix the order of the rules.

	* src/benchs/generate_all_benchs.sh: Remove, merged into...
	* src/benchs/generate_benchs.sh: this.
	Adjust uses.
	Introduce functions to clarify this program.
	* src/tests/test-suites/Makefile.am: Ship it.

	* configure.ac: Pass nostdinc to Automake to avoid useless -I on
	already too long command lines.
	All the uses must be adjusted to pass -I$(top_builddir) for
	config.h.
	So a Makefile snippet to factor all this would be most welcome.
	* src/vaucanson.mk: New.
	* src/taf-kit/Makefile.am: Use it.
	* src/benchs/common/Makefile.bench: Rename as...
	* src/benchs/common/bench.mk: this.
	Don't use INCLUDES, it is not defined.
	* src/tests/check/Makefile.flags,
	* src/benchs/common/bench.mk: Adjust to nostdinc.

	* src/demos/demo.mk: New.
	* src/demos/algorithms/Makefile.am: Use it.
	* src/demos/function_library/Makefile.am,
	* src/demos/automaton_library/Makefile.am,
	* src/demos/utilities/vgrep/Makefile.am,
	* src/demos/transducers/one_rule_rewriting/Makefile.am,
	* src/demos/transducers/Makefile.am: Ditto.

	* src/tests/bin/generate-test-suite.sh:
	Don't use "env", it's useless.