Emplace modified coefficients directly instead of via shifts

Also add some more tests for edge cases in BigIntPoly.mul().
Avoid calling BigIntPoly.getCoefficientCount() repeatedly

Add comments about how the bytes in the unused capacity of
BigIntPoly.phi are used.
Use flag package
Add a -j flag for number of jobs
Add an -end flag for the upper bound to use
Add a -cpuprofile flag for profiling
Rework directory structure to follow go standards

http://golang.org/doc/code.html describes how code should be structured.
Make BigIntPoly a private type (bigIntPoly)
Privatize all functions in arith.go (except for FloorRoot())
Avoid use of aks.FloorRoot() in aks-go/bin-src/aks.go and privatize it
Make aks.GetAKSWitness() take a start and end parameter
Add a -start flag for the lower bound to use