Define separate FX for LV-N's LF and LH2 modes

KSP apparently doesn't like sharing the same effect definitions between several
engine modules; only one of them actually plays the effect.  To get the effects
on both engine modes, they have to be defined twice, with different names.

To avoid duplicating all the effect properties, I've used ModuleManager's
whole-node copy-paste feature to copy the AUDIO and MODULE_MULTI_PARTICLE nodes
from the LH2 effects to the LF ones.

GameData/KerbalAtomics/Patches/NTR/hydrogenNTRsSQUAD.cfg

@@ -73,6 +73,17 @@
 				speed = 1.0 1.0
 			}
 		}
+		fx-sc-lf-core
+		{
+			// Copy from the corresponding LH2 effect.
+			#../fx-sc-lh2-core/AUDIO {}
+			#../fx-sc-lh2-core/MODEL_MULTI_PARTICLE {}
+		}
+		fx-sc-lf-plume
+		{
+			// Copy from the corresponding LH2 effect.
+			#../fx-sc-lh2-plume/MODEL_MULTI_PARTICLE {}
+		}
 	}
 	MODULE
 	{
@@ -111,8 +122,8 @@
 		engineID = LF
 		thrustVectorTransformName = thrustTransform
 		exhaustDamage = True
-		runningEffectName = fx-sc-lh2-core
-		powerEffectName = fx-sc-lh2-plume
+		runningEffectName = fx-sc-lf-core
+		powerEffectName = fx-sc-lf-plume
 		ignitionThreshold = 0.1
 		minThrust = 0
 		maxThrust = 60