implementing logstorage inverted indexing
 * changed index schema confdb collection name
 * support index search for multiple indexes
 * search also buffered index token (at online indexer)
 * support online indexer status query
added fulltext search command
getLog() returns memory buffered (flush waiting) log
 * added batch index build monitoring
 * cancel batch index build when dropping index
added index file header (magic string | version | length | map
encoded by kraken codec)
added index merging function
 * fixed log cursor leak
 * added batch-online index merge
added delete/merge locking (prevent file access)
added license terms
added cached random log seeker interface to prevent repetitive log
file open at index seek
 * fixed index cursor leak
 * use new cached random log seeker for speedup
support index tokenizer configuration
sort term block and enhanced term search speed (break if no more term
can be found)
added query details to 'queries' msgbus call
 * added simple index unit test
added log/index retention policy and periodic purging
remove retention policy when drop table
added more parameter verification to confdb
Merge branch 'logstorage-indexing'