Parser: Alignment Constraints for MemoryState

[achreto]

Problem

Currently, we do have no way to express constraints on the parameters (e.g., the base addresses and length of states etc).
This is important as we need to be able to allocate in-memory data structures (e.g., page tables) correctly.

Proposed Solution
Have something that allows expressing of constraints on the unit parameters. That includes

• alignment constraints on the input values
• total length of the memory region passed in

This may be related to: #54