v3.2.0

• Allow NewBufferPool to set the buffer size.
• Add the default signal sets DefaultSignals, and HandleSignal will use DefaultSignals if not appointing the signals.
• Add the function ReadNWriter.
• Add the function GeneralDecoder.
• Add the function CheckError.
• Add the functions RangeStop, RangeStepOne, Ranges.
• Add some global default buffer pool and bytes pools.
• Add CA arguments for ListenAndServe() and deprecate ListenAndServeTLS().
• Fix: correct the replacement ~ and $HOME in Abs().
• Fix: add the lock for SizedRotatingFile.DisableBuffer().