Primary updates

[slowe]

Requests for changes to Primaries from @mary-black

1. Merge FAWDON T1 and SEATON BURN T1 into one Primary with the splits:
   • Newcastle upon Tyne: 0.513905
   • North Tyneside: 0.310481
   • Northumberland: 0.175614
     The new name is FAWDON T1 & SEATON BURN T1
2. Add five new "cut-outs":
   • GUISBOROUGH T3: 461116, 516771 Redcar
   • LEAM CENTRAL: ? Gateshead
   • SCARBOROUGH 66/11KV: 503373, 486618 Scarborough
   • STOBSWOOD COAL: ? Northumberland
   • SUNDERLAND T5 T6: 438979, 557599 Sunderland

[slowe]

@mary-black These should now be added. You can see the merger for FAWDON T1 & SEATON BURN T1 at c9540e6 and the additions (including holes) for the Primaries at a8f47b9

[slowe]

I had to use nearby.org.uk to convert grid references to lat/lon. For the postcodes I used findthatpostcode and then looked at satellite/street views of the lat/lon to see how close the postcodes were to things that looked like electricity substations.