treewide: "require" + "use" cleanup and docs

There's a bunch of leftover "require" and "use" statements we no
longer need and can get rid of, along with some excessive
imports via "use".

IO::Handle usage isn't always obvious, so add comments
describing why a package loads it.  Along the same lines,
document the tmpdir support as the reason we depend on
File::Temp 0.19, even though every Perl 5.10.1+ user has it.

While we're at it, favor "use" over "require", since it it gives
us extra compile-time checking.

1 files changed, 0 insertions, 2 deletions

diff --git a/t/cgi.t b/t/cgi.t
index 90543a7a..9f67d5c0 100644
--- a/t/cgi.t
+++ b/t/cgi.t
@@ -32,8 +32,6 @@ EOF
         close $fh or die "close: $!\n";
 }
 
-use_ok 'PublicInbox::Git';
-use_ok 'PublicInbox::Import';
 use_ok 'PublicInbox::Inbox';
 use_ok 'PublicInbox::InboxWritable';
 use_ok 'PublicInbox::Config';