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, 2 insertions, 2 deletions

diff --git a/lib/PublicInbox/HTTPD.pm b/lib/PublicInbox/HTTPD.pm
index 47f5a01a..1331a91e 100644
--- a/lib/PublicInbox/HTTPD.pm
+++ b/lib/PublicInbox/HTTPD.pm
@@ -7,8 +7,8 @@ package PublicInbox::HTTPD;
 use strict;
 use warnings;
 use Plack::Util;
-require PublicInbox::HTTPD::Async;
-require PublicInbox::Daemon;
+use PublicInbox::HTTPD::Async;
+use PublicInbox::Daemon;
 
 sub pi_httpd_async { PublicInbox::HTTPD::Async->new(@_) }