Added Proposal Algorithm

App can now propose how settlements can be made.
Slight refinement in Proposal Algo
PaymentActivity ready

Now it is possible for multiple participants to pay for multiple
recepients, with logging and math support. This concludes Phase I.
Cleanup

Small UI fixes, displaying correct values in log.
Improvement in Proposal Algo

New improvement ignores small amount of change in order to avoid loop
due to rounding off of values.
Reset payees

Payees are reset if the Add button is pressed again