Change variable names in the gaussian fittings

Change variable names in the gaussian fittings as follows.

- offset_az
- offset_el
- offset_az_error
- offset_el_error
- hpbw_major
- hpbw_minor
- hpbw_major_error
- hpbw_minor_error
- position_angle
- position_angle_error
- peak
- peak_error
- floor
- floor_error
- chi2
- reduced_chi2