New I/O message type: active messages (can be used for boot protocol).
Minor cleanup of the INVALID_* definitions.
Simplify the SMC.
Simplify the ActiveROM.
Let the ActiveROM send an active message upon boot (replaces SMC).
Cleanup whitespace.
Let DRISC::IOInterface discover its SMC automatically.
Perform register initialization in DRISC::Initialize.
Enable booting DRISC via active message on I/O.
Ensure registers are initialized after 1st thread is allocated.
Add missing include to fix compilation of area.cpp.
Simplify bundle creation.