In Java it is possible to create an object by knowing its class name in
runtime. Replication strategies are created this way (I presume class
name comes from configuration somehow), so when I translated the code to
urchin I wrote replication_strategy_registry class to map a class name to
a factory function. Now I see that this is used in other places too (I
see that snitch class created in the same way), so instead of repeating
the same code for each class hierarchy that is created from its name in
origin this patch tries to introduce an infrastructure to do that easily.
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>