Added missing electric decomp values.

Added missing "decomp_learn" values to these:
Directional Antenna
Amplifier
Receiver
Transponder
battery_compartment has "autolearn": true, and "decomp_learn" was the same as difficulty, should be removed? I lowered it one level so its not completely meaningless.
Having learned how these work (by taking them apart) myself, as a child.
I figured they must have just been missed.