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, 1 insertions, 1 deletions

diff --git a/lib/PublicInbox/WatchMaildir.pm b/lib/PublicInbox/WatchMaildir.pm
index 7803b58a..8a8c1262 100644
--- a/lib/PublicInbox/WatchMaildir.pm
+++ b/lib/PublicInbox/WatchMaildir.pm
@@ -9,7 +9,7 @@ use warnings;
 use PublicInbox::MIME;
 use PublicInbox::Spawn qw(spawn);
 use PublicInbox::InboxWritable;
-use File::Temp 0.19 ();
+use File::Temp 0.19 (); # 0.19 for ->newdir
 use PublicInbox::Filter::Base qw(REJECT);
 use PublicInbox::Spamcheck;
 *maildir_path_load = *PublicInbox::InboxWritable::maildir_path_load;