* origin/search:
view: deduplicate common code for loading search results
SearchMsg: ensure metadata for ghost messages mid
implement /s/$SUBJECT_PATH.html lookups
search: remove unnecessary xpfx export
www: /t/$MESSAGE_ID.html for threads
view: hoist out index_walk function
view: reply threading adjustment
thread: common sorting code
view: display replies in per-message view
search: make search results more OO
extract redundant Message-ID handling code
search: implement index_sync to fixup indexer
initial search backend implementation