Previously, the show schema and the search schema used different
"thread" non-terminals. While these schemata don't interact, this is
still confusing, so rename search's "thread" to "thread_summary". To
further limit confusion, prefix all top-level search non-terminals now
begin with "search_".
---------------------
# --output=summary
---------------------
# --output=summary
+search_summary = [thread_summary*]
+search_threads = [threadid*]
+search_messages = [messageid*]
+search_files = [string*]
thread: threadid,
timestamp: unix_time,
date_relative: string, # user-friendly timestamp
thread: threadid,
timestamp: unix_time,
date_relative: string, # user-friendly timestamp