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/script/public-inbox-init b/script/public-inbox-init
index da683657..34c93b47 100755
--- a/script/public-inbox-init
+++ b/script/public-inbox-init
@@ -14,8 +14,8 @@ EOF
 use Getopt::Long qw/:config gnu_getopt no_ignore_case auto_abbrev/;
 use PublicInbox::Admin;
 PublicInbox::Admin::require_or_die('-base');
-require PublicInbox::Config;
-require PublicInbox::InboxWritable;
+use PublicInbox::Config;
+use PublicInbox::InboxWritable;
 use File::Temp qw/tempfile/;
 use PublicInbox::Lock;
 use File::Basename qw/dirname/;