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.