Small updates + more support for emulation

This adds a ``doStuff()`` virtual function to ``VMEController``.  ``oRSCEmulator`` overrides this to do an echo feature (xref #7).  Let me know if it makes sense to you.  Right now doing 
```
mkfifo txbuffer rxbuffer
bin/vme2fd txbuffer rxbuffer
echo "hello" > txbuffer
cat rxtbuffer
```
returns ``hell`` (missing an o).  So it is a start but there is still some  overflow issue (NB ``hell`` is 32 bits).