0.4.0 Release

Features:

• mget improve (idning)
• many new commands supported: LEX, PFADD, PFMERGE, SORT, PING, QUIT, XSCAN... (mattrobenolt, areina, idning)
• handle max open file limit(allenlz)
• log: add notice-log and use ms time in log(idning)

Fix:

• bug in string_compare (andyqzb)
• deadlock in sighandler (idning)

Others:

• add many Utils link like redis-mgr, smitty.