Changes

The changes are few but with big footprints:

Dry mass balance on all parts. (They were largely excessively heavy but they should meet CryoTanks' standard now)
Rewrote engines to not be handwavium by default:
- Except the warpjets are still warpjets
- The Dark Drive is now an antimatter engine, and the Bubble engine might be in a weird place, possibly unusable
- The J61 engine has been made into scramjet only. (Doesn't function under Mach 4 speeds.) I should undo that, probably? Lots of people like it being an all-range engine but it's really OP as a short engine but its complement, the short HAE-02 turboramjet exists, and its true equivalent, the J-60 Screamjet exist. Fixing the J61 will break the most craft files (and hearts) 💔
Made some changes and reductions in RO support.
Some changes to the fusion power spheres.

Suggestions

Install RR Jet Family (v 2.0.4 or later) for fuel switching in the LFO engines. They can choose between LFO, Hydrolox and Methalox.
Install RR Nuclear Family for balancing the engines that have been converted to thermal nozzles. (ThermalPower sources not added/included in OPT)