* plugin.cpp: Revert back to 5.0 support.
Merge branch '4_9-plugin'
* README.md: Add goals, FAQ, etc.
* runtime_sigprof.cpp (freqency): 100 is also okay.
(MAX_STACK): Rename to max_stack. And disconnected with freqency.
(other functions): Rename MAX_STACK.
* runtime_sigprof.cpp: Always update current time(not thread time) on first entry of __start_entry.
* runtime_sigprof.cpp (struct CTraceStruct): New fields. To record thread
times.
(struct ThreadInfo): New field. To record thread time.
(CTraceStruct::CTraceStruct): Delete the initialization of min_end_time_.
We don't care it, so don't waste time.
(MyHandler): Update time & thread time accordingly.
(struct Record): New fields. Similar.
(RecordThis): Update. Similar.
(DoWriteRecursive): Write thread times.
(__start_ctrace__): Delete useless updates.
(__end_ctrace__): Update thread mini end time.
Update README.md
* license.txt: Add LGPL license declaration.
Merge branch 'master' into 4_9-plugin
* license.txt: Add LGLP license.
Conflicts:
	README.md