fid_proc support and various bug fixes

[VKarlaftis]

• Expanded support to fid_proc.64 files ('fid_proc' differs from 'fid' in regards to where the file is stored relative to the parameter_files, see RELATIVE_PATHS code)
• Bug fix on deleting non-existent attributes in unload_properties
• Bug fix on _validate method as all parameter_files were expected inside the parent folder instead of the specific paths defined in RELATIVE_PATHS.
• Bug fix on dwell_s when sw_hz is zero
• Relaxed assertion of binary file size on disk vs expected from code (otherwise it fails every time)