Added clf-check utility

This merge adds the clf-check command-line utility, which compares channels in list file to those in GWF files, and prints verbose output, e.g:

$ python tools/clf-check O2/L1-O2-standard.ini
Read list file [O2/L1-O2-standard.ini]
Checking 'Calibrated h(t)':
    Identified 1 channels
    Finding channels for L1_HOFT_C00:
        Identified GWF: /archive/frames/postO2/hoft/L1/L-L1_HOFT_C00-12021/L-L1_HOFT_C00-1202135040-4096.gwf
        Read 16 channels
    No missing channels
Checking 'Length sensing and control':
    Identified 28 channels
    Finding channels for L1_R:
        Identified GWF: /archive/frames/postO2/raw/L1/L-L1_R-12021/L-L1_R-1202142016-64.gwf
        Read 227309 channels
    No missing channels
Checking 'Arm Length Stabilization':
    Identified 2 channels
    No missing channels
Checking 'Alignment Sensing and Control':
    Identified 56 channels
    No missing channels
Checking 'Alignment Sensing and Control: slow':
    Identified 20 channels
    No missing channels
Checking 'Photon Calibrator':
    Identified 4 channels
    No missing channels
Checking 'Hydraulic (External) Pre Isolator':
    Identified 88 channels
    No missing channels
Checking 'Input Mode Cleaner':
    Identified 46 channels
    No missing channels
Checking 'Internal Seismic Isolation: BSC ISI ST1 T240s':
    Identified 30 channels
    No missing channels
Checking 'Internal Seismic Isolation : optics table GS13s':
    Identified 60 channels
    No missing channels
Checking 'Internal Seismic Isolation : ground motion STS2s':
    Identified 15 channels
    No missing channels
Checking 'Output Mode Cleaner':
    Identified 15 channels
    No missing channels
Checking 'Output Mode Cleaner: slow':
    Identified 2 channels
    No missing channels
Checking 'Physical Environment Monitoring: Accelerometers':
    Identified 51 channels
    Found 6 missing channels:
        L1:PEM-CS_ACC_IOT1_IMC_Z_DQ
        L1:PEM-CS_ACC_IOT1_IMC_X_DQ
        L1:PEM-EY_ACC_ISCTEY_TRANS_X_DQ
        L1:PEM-CS_ACC_IOT1_IMC_Y_DQ
        L1:PEM-EX_ACC_ISCTEX_TRANS_Y_DQ
        L1:PEM-CS_ACC_ISCT6_OMC_X_DQ
Checking 'Physical Environment Monitoring: Low frequency microphones':
    Identified 3 channels
    No missing channels
Checking 'Physical Environment Monitoring: Magnetometers':
    Identified 31 channels
    No missing channels
Checking 'Physical Environment Monitoring: Mains voltage monitors':
    Identified 15 channels
    Found 2 missing channels:
        L1:PEM-CS_ADC_4_20_OUT_DQ
        L1:PEM-CS_ADC_4_21_OUT_DQ
Checking 'Physical Environment Monitoring: Microphones':
    Identified 11 channels
    No missing channels
Checking 'Physical Environment Monitoring: Radio frequency receivers':
    Identified 7 channels
    Found 1 missing channels:
        L1:PEM-CS_RADIO_LVEA_IMC_DQ
Checking 'Physical Environment Monitoring: Seismometers':
    Identified 15 channels
    No missing channels
Checking 'Pre Stabilized Laser':
    Identified 9 channels
    No missing channels
Checking 'Suspensions: Optical levers':
    Identified 21 channels
    No missing channels
Checking 'Suspension: OSEMs':
    Identified 204 channels
    No missing channels
Checking 'Suspension: Noise Monitors':
    Identified 108 channels
    No missing channels
Checking 'Suspension: Noise Monitors : slow':
    Identified 12 channels
    No missing channels
Checking 'Thermal Compensation':
    Identified 4 channels
    No missing channels

There are 9 missing channels across all sections:
L1:PEM-CS_RADIO_LVEA_IMC_DQ
L1:PEM-CS_ACC_IOT1_IMC_Y_DQ
L1:PEM-CS_ADC_4_20_OUT_DQ
L1:PEM-CS_ADC_4_21_OUT_DQ
L1:PEM-CS_ACC_IOT1_IMC_Z_DQ
L1:PEM-CS_ACC_IOT1_IMC_X_DQ
L1:PEM-EX_ACC_ISCTEX_TRANS_Y_DQ
L1:PEM-EY_ACC_ISCTEY_TRANS_X_DQ
L1:PEM-CS_ACC_ISCT6_OMC_X_DQ