Update to the calibrate.sensormodel table.  Modifications were made based on usarray calibrations where the following data were used:

sensor     - sensor type
ncals      - number of calibrations run
nsn        - number of unique serial numbers
sngen_old  - original sngen
correction - correction factor
sngen_new  - updated sngen

sensor          ncals   nsn     sngen_old       correction      sngen_new

cmg3t           1731    172     2.1730000e-02   1483.1/1500     2.1485175e-02
sts2_5            60     15     3.0023787e-02   2115.2/1500     4.2337543e-02
sts2_g3         2714    251     3.0023787e-02   1534.4/1500     3.0712332e-02
trillium_240_1   503     51    -9.0375000e-01   1205.9/1200    -9.0819344e-01
trillium_240_2   337     61    -9.0375000e-01   1197.7/1200    -9.0201781e-01

also corrected nominal trillium 240 responses to 1200 V/m/sec.