Make install-sh work even when names contain spaces or

	Make install-sh work even when names contain spaces or
	certain (but not all) shell metachars.

	* lib/install-sh: Remove lots of unnecessary quoting.
	Add double quotes where necessary.
	Write diagnostics to stderr, not stdout.
	Normalize spacing in diagnostics: use one space (not two,
	and not a TAB) after the leading `install:'.
	Remove trailing white space.
	Remove unnecessary curly braces.
	If removing the destination fails, also try to move it aside.
	Use `trap' more portably.
	* tests/installsh2.test: New file, to test for the above fix.
	* tests/Makefile.am (TESTS): Add installsh2.test.