refactor: release 0.5.0

merge code in bookug branch

by zengli

move devGstore to gStore and go on working on github instead of git osc;

 improve the init configure file;
 support empty database and indices:you can remove all triples from a db and insert/query;
 change signature struct and generating method in build;
change FIFO to LRU; fix bug in Signature, the int maybe overflow;
test on shape.db, 0.7B triples with 0.42B entities

Merge branch 'master' of https://github.com/Caesar11/gStore

merge with subtle updates from github user, and then merge 0.4.0

add postProcessing and stringIndex for getFinalResult;add insertion/d…

…eletion;fix bugs

fix bug in distributed gstore, Join::preFilter

add insertion and deletion;move new version here

reduce the code size of old gstore

add php api