Create a framework for alias analysis

[errt]

We already have a points-to framework that produces results that can be used for alias analysis. Other options might include a simple intra-procedural alias analysis from def-use information and an IFDS/IDE-based analysis.
For these, a unified lattice should be implemented to be used by other analyses and one or two simple analysis implementations as outlined above should be provided.

[errt]

Completed in #194.