Highlight more Perl quoting syntaxes

This adds highlighting for

- quoting operators qw, qr, and qx, like `qw< some words >`
- angle brackets after a quoting operator, like `q<string>`
- punctuation as quoting delimiter, like `q|string|`
- POD sections, which start with ^=\w and and with ^=cut
- heredocs; the marker can be a bare word, or a quoted word, like

	print <<~ 'EOF'
		single quoted heredoc
	EOF

Closes #3736

No attempt is made to use different highlighting for interpolated (qq or
"") strings just yet. Recognizing quote boundaries is more important.

0 files changed, 0 insertions, 0 deletions