UserspaceEmulator: Start sketching out a SoftMMU class :^)

This Emulator sub-object will keep track of all active memory regions
and handle memory read/write operations from the CPU.

A memory region is currently represented by a virtual Region object
that can implement arbitrary behavior by overriding read/write ops.

DevTools/UserspaceEmulator/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(SOURCES
     SoftCPU.cpp
+    SoftMMU.cpp
     Emulator.cpp
     main.cpp
 )