[stdlib/prototype] Replace multiprecision addition
[stdlib/prototype] Replace multiprecision addition

Generalized, made it more correct, basic structure works for subtraction.

apple/swift,OscarSwanros/swift,frootloops/swift,frootloops/swift,alblue/swift,kstaring/swift,practicalswift/swift,uasys/swift,milseman/swift,kperryua/swift,shajrawi/swift,manavgabhawala/swift,xedin/swift,austinzheng/swift,hooman/swift,parkera/swift,gribozavr/swift,austinzheng/swift,practicalswift/swift,stephentyrone/swift,adrfer/swift,dduan/swift,glessard/swift,stephentyrone/swift,KrishMunot/swift,ahoppen/swift,nathawes/swift,devincoughlin/swift,brentdax/swift,danielmartin/swift,hughbe/swift,jtbandes/swift,russbishop/swift,gmilos/swift,alblue/swift,deyton/swift,shahmishal/swift,parkera/swift,IngmarStein/swift,benlangmuir/swift,codestergit/swift,frootloops/swift,tkremenek/swift,therealbnut/swift,codestergit/swift,tardieu/swift,SwiftAndroid/swift,lorentey/swift,xedin/swift,modocache/swift,allevato/swift,nathawes/swift,allevato/swift,SwiftAndroid/swift,gregomni/swift,swiftix/swift,sschiau/swift,kstaring/swift,sschiau/swift,jtbandes/swift,deyton/swift,hooman/swift,SwiftAndroid/swift,brentdax/swift,russbishop/swift,ken0nek/swift,parkera/swift,djwbrown/swift,calebd/swift,huonw/swift,kstaring/swift,hooman/swift,gribozavr/swift,tkremenek/swift,allevato/swift,hooman/swift,gmilos/swift,therealbnut/swift,roambotics/swift,shajrawi/swift,kstaring/swift,xwu/swift,shajrawi/swift,ben-ng/swift,tjw/swift,benlangmuir/swift,rudkx/swift,austinzheng/swift,alblue/swift,shahmishal/swift,hughbe/swift,shajrawi/swift,austinzheng/swift,gottesmm/swift,rudkx/swift,therealbnut/swift,practicalswift/swift,harlanhaskins/swift,adrfer/swift,bitjammer/swift,parkera/swift,aschwaighofer/swift,JGiola/swift,gribozavr/swift,JGiola/swift,sschiau/swift,manavgabhawala/swift,frootloops/swift,benlangmuir/swift,slavapestov/swift,tardieu/swift,Jnosh/swift,stephentyrone/swift,lorentey/swift,rudkx/swift,jckarter/swift,airspeedswift/swift,manavgabhawala/swift,xedin/swift,sschiau/swift,shajrawi/swift,jtbandes/swift,CodaFi/swift,IngmarStein/swift,devincoughlin/swift,gregomni/swift,johnno1962d/swift,CodaFi/swift,swiftix/swift,felix91gr/swift,hughbe/swift,Jnosh/swift,ken0nek/swift,kperryua/swift,shajrawi/swift,airspeedswift/swift,modocache/swift,gregomni/swift,shahmishal/swift,jmgc/swift,calebd/swift,stephentyrone/swift,natecook1000/swift,gregomni/swift,kperryua/swift,milseman/swift,swiftix/swift,IngmarStein/swift,jmgc/swift,KrishMunot/swift,lorentey/swift,jmgc/swift,tinysun212/swift-windows,russbishop/swift,tkremenek/swift,amraboelela/swift,harlanhaskins/swift,nathawes/swift,devincoughlin/swift,practicalswift/swift,aschwaighofer/swift,brentdax/swift,modocache/swift,KrishMunot/swift,glessard/swift,gregomni/swift,gmilos/swift,practicalswift/swift,deyton/swift,tjw/swift,tjw/swift,IngmarStein/swift,ben-ng/swift,dreamsxin/swift,kperryua/swift,swiftix/swift,manavgabhawala/swift,swiftix/swift,OscarSwanros/swift,bitjammer/swift,lorentey/swift,danielmartin/swift,jckarter/swift,atrick/swift,calebd/swift,zisko/swift,djwbrown/swift,therealbnut/swift,nathawes/swift,calebd/swift,gribozavr/swift,gottesmm/swift,alblue/swift,JaSpa/swift,xedin/swift,JGiola/swift,CodaFi/swift,glessard/swift,djwbrown/swift,hughbe/swift,atrick/swift,danielmartin/swift,ahoppen/swift,kstaring/swift,shahmishal/swift,slavapestov/swift,johnno1962d/swift,airspeedswift/swift,ahoppen/swift,johnno1962d/swift,codestergit/swift,return/swift,karwa/swift,harlanhaskins/swift,karwa/swift,OscarSwanros/swift,IngmarStein/swift,kstaring/swift,gottesmm/swift,huonw/swift,arvedviehweger/swift,stephentyrone/swift,russbishop/swift,ken0nek/swift,return/swift,amraboelela/swift,tjw/swift,lorentey/swift,lorentey/swift,stephentyrone/swift,jtbandes/swift,practicalswift/swift,gregomni/swift,jckarter/swift,devincoughlin/swift,roambotics/swift,parkera/swift,roambotics/swift,huonw/swift,rudkx/swift,OscarSwanros/swift,danielmartin/swift,shahmishal/swift,atrick/swift,hooman/swift,sschiau/swift,xwu/swift,felix91gr/swift,shajrawi/swift,johnno1962d/swift,return/swift,calebd/swift,adrfer/swift,arvedviehweger/swift,ben-ng/swift,tinysun212/swift-windows,codestergit/swift,stephentyrone/swift,tardieu/swift,xedin/swift,return/swift,tjw/swift,slavapestov/swift,ben-ng/swift,huonw/swift,tinysun212/swift-windows,sschiau/swift,SwiftAndroid/swift,djwbrown/swift,felix91gr/swift,manavgabhawala/swift,harlanhaskins/swift,jopamer/swift,apple/swift,lorentey/swift,therealbnut/swift,ben-ng/swift,JaSpa/swift,jopamer/swift,tardieu/swift,jmgc/swift,hughbe/swift,tjw/swift,sschiau/swift,JaSpa/swift,shajrawi/swift,jmgc/swift,zisko/swift,felix91gr/swift,ben-ng/swift,jopamer/swift,jckarter/swift,xedin/swift,Jnosh/swift,JaSpa/swift,practicalswift/swift,natecook1000/swift,deyton/swift,austinzheng/swift,karwa/swift,hooman/swift,glessard/swift,johnno1962d/swift,JaSpa/swift,slavapestov/swift,gmilos/swift,xwu/swift,amraboelela/swift,allevato/swift,OscarSwanros/swift,JaSpa/swift,bitjammer/swift,hooman/swift,arvedviehweger/swift,bitjammer/swift,alblue/swift,jtbandes/swift,modocache/swift,apple/swift,return/swift,austinzheng/swift,ben-ng/swift,JGiola/swift,airspeedswift/sw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