Added new warnings as defined by Pod::Checker, thanks to RJBS:
- "=over" without "=back"
- "L<>" starts or ends with whitespace
- raw "|" or "/" in "L" text
- "=over" without "=back"
Added ->keep_encoding_directive, which is false by default, to
prevent formatters from emitting a document's '=encoding'
directive in most cases. That they emitted the encoding was a bug
introduced in v3.26 (RT #84093). Now, only the DumpAsText and
DumpAsXML formats set it to true. Patch from Patrice Dumas.