Updates for latest SoapySDR 0.5 series

[guruofquality]

• parameterize setHardwareTime(), deprecate setCommandTime() In SoapySDR, we have a parameterized setHardwareTime() call for setting arbitrary timestamps. Recently, setCommandTime() has been deprecated in favor of using the parameterized setHardwareTime(). Do the matching work in SDR blocks by given setHardwareTime a "what" parameter as well.
• mark setCommandTime() deprecated
• switch to bandwidth range over bandwidth list of doubles. See getBandwidths() call in SDRBlock.cpp