Add FunUniverse/Fin/Op.agda
FunUniverse.Agda: Two can be left abstract now
FunUniverse.BinTree: without-K
FunUniverse.Bits: update
FunUniverse.Category: layout
FunUniverse.{Core,Data}: adapt to Two
FunUniverse.Fin: add finCat
FunUniverse.Nand: rename fork as mux
FunUniverse/Rewiring/Linear: add mapAccum
Fix a note
Cost: adapt to Two
Add FunUniverse/Fin/Op/Abstract.agda
Add FunUniverse/Category/Op.agda
adder: use mapAccum
Add FunUniverse/Nand/Function.agda
Add FiniteField/FinImplem.agda (unfinished)