#473 Add new CBL_GC_SCR_DUMP and RESTORE routines

[Eugenio Di Lorenzo]

The two new routines CBL_GC_SCR_DUMP and CBL_GC_SCR_RESTORE have recently been released.
Their documentation have to be added to the PG.
Attached is the content already in LATEX format (I hope it is correct ...).

[Vincent (Bryan) Coen]

As these have NOT been made avilable tot he code base I cannot do anything with them let alone seeing the formal specifications of each.

[Vincent (Bryan) Coen]

Done