ProjectFramework quantity suffix

[RomeshA]

Proposed functionality: Add a suffix to every quantity in the framework to enable two frameworks to be safely stitched together if they both have different suffixes added to them

e.g.

Framework 1: sus -> sus@malaria
Framework 2: sus -> sus@tb
Combined framework: contains sus@malaria and sus@tb

The stitching would likely be done outside Atomica but adding suffixes correctly is tightly coupled to the Atomica implementation and might be easiest to implement here