Draft: Split AllenLib into smaller libraries

Still WIP:

Testing splitting the (very large) AllenLib into 3 libaries:

• AllenLibHost (Host Algos)
• AllenLibDevice (Device Algos not including PVs)
• AllenLibDevicePV (Device Algos for PVs)

Device algos into two libraries, to see if the CUDA objects can be successfully linked across the libs.

Doing this also requires moving extern __constant__ variables into their own library, this is called Constants living in device

Separately, it also allows any capitalisation of -DSEQUENCE=all instead of insisting on lower case