Make emulator output match unpacker/GT expectation

I'm using this pull request to track my work on changing the output of the emulator so that the eta coordinates and et scales match the GT expectations (as the unpacker output will use). It definitely shouldn't be merged until I've at least got the hardware parts working - the PhysicalEtAdder parts are secondary.

So far I've added the needed conversion scales to the CaloParams object (maybe not a good idea) and changed both jet algorithms to using the conversion code in legacyGtHelper.{cc,h}. Suggestions welcome.