Draft: Perturbate Unique keys in UniqFM (fixed)

Fixes the compiler panics in MR!5068. The panics were caused by #ifdef UNIQUE_TAG_BITS == 8 evaluating to the else branch even on 64-bit machines. Which was due to the missing #include Unique.h which defines UNIQUE_TAG_BITS.

Just a draft, we need to look at the compiler and runtime performance before an actual merge. It could be the case that the extra enc and dec around UniqFM functions are too costly.