remove NOISEFLOOR_CALIBRATION and ADC_DYNAMIC_RANGE constants

replace with REFLEVEL_ERROR and normalized reflevel calculation
HDR usable bins good, SH+fshift not
remove forgotten code
remove dead code
better hdr bottom and min dbm settings
Merge pull request #34 from wardi/remove-adc-constants

remove NOISEFLOOR_CALIBRATION and ADC_DYNAMIC_RANGE properties