Basics of SegCore calibration now working.  Now just need to convert seg-core coeffs and core-energy coeffs into seg-energy coeffs.
More minor edits to SegCore calibration.  Have a plan now so this will shape up quickly in next few commits.
- Changed Seg-core charge fit to custom function.
- order of fit now set in config.
- initial values of seg coeffs written out.
Integration now included in calculation of seg gain coeffs.
Seg gain coeffs now calculated for seg-core correlation order up to three.
Plotting of SegCore calibtration now controlled from Options.C/-p switch at command line.
Some tidying.
Seg coeffs are now properly calculated using correct core coeffs.
Everything seems to be working, hope I haven't broken anything.