update iconv.hpp and use gtest for unit test
	modified:   Makefile.am
	modified:   Makefile.in
	modified:   configure
	modified:   configure.ac
	new file:   example/Makefile.am
	new file:   example/Makefile.in
	renamed:    test/test.cpp -> example/test.cpp
	modified:   include/iconv.hpp
	modified:   test/Makefile.am
	modified:   test/Makefile.in
	new file:   test/aclocal.m4
	new file:   test/config.h.in
	new file:   test/configure
	new file:   test/configure.ac
	new file:   test/gtest/gtest-all.cc
	new file:   test/gtest/gtest.h
	new file:   test/gtest/gtest_main.cc
	modified:   test/test.cpp