Use bytebuffer to capture fractional words and prebaked fd writing tools
Always append data if it has been buffered from input

Even if we haven't read anything in this event loop.
Store registers by value
Use a realistic size (512 words) for VME block RAM
whitespace
Remove debug output
Use VMEStream on the emulator
Tyep of emulation behavior now specified by OrscEmulator subclass
Work in progress IPBus emulator