Log: add silent log level
Log: change default log level to LEVEL_INFO
Log: add newline for printf log
WatcherThread: add some useful log
add Pair class
WatcherThread: merge split index in different thread
client: add position to terms view
client: terms_view: add term filter
Document: remove abstract
Document: add last indexed field
Document: add index complete field
TermsCollection: rename getPostList to getPostingList
TermsCollection: add getPosting
WatcherThread: limit open file when indexing