break the analysis pipeline into components

[amandasystems]

Currently, the each Poloniu Algorithm's compute() method performs initialisation analysis, then liveness calculations, and then the actual Polonius implementation. This means a lot of code duplication and in the case of the hybrid algorithm that all of this happens twice.

I suggest the following for a minimal modification to the current setup:

• the publicly visible compute() method still takes the gigantonormous AllFacts for now
• internally, these facts are split up into internal data structures consumed by the various compute() methods
• the calls initiating initialisation and liveness calculations happen in output::compute()