* ampc.el: Optimise parsing of MPD's output.
(ampc-iterate-source): Cache delimiter if it should be bound. Compute delimiter
regexp at compile time.
(ampc-iterate-source-output): Cache tags and tag regexps.
(ampc-extract-regexp): New macro.
(ampc-extract): Inline function. Pass regexp rather than tag. Refactor tag
cleaning to ampc-clean-tag.
All callers changed.
(ampc-clean-tag): New function.
(ampc-narrow-entry): Inline function. Do not modify point. Return start of
delimiter match.