simple level from one backend, such as the gbz80 and z80.
3. Provide a way to dynamically build a command line for any spawned
processes.
-4. Provide a way for the backend to convientely access volatile global data
+4. Provide a way for the backend to conveniently access volatile global data
such as the source file name or current function name. This is mainly
to get around assembler limitations.