Clarifications, etc.:
<ul>
<li>The project description says "memory should be initialized to zero at start of a run". This should take place <i>before</i> you write instructions into it...
<li>Register and instruction names are case sensitive, i.e. 'Load' is
	acceptable, 'load' is not, 'r2' is not.
<li>writes to R1 should be caught at runtime in the interpreter. Return -1.
<li>labels are only alphanumeric characters, and must start w/ a-z (either case).
<li>'output' should write the register to STDOUT, followed by a carriage return.
<li>Incrementing of the PC (register 1) is part of the fetch and
decode phase of instruction execution. As such, it should be completed
<i>before</i> an instruction is actually executed.
<li>There are no blank lines in any of the test cases.
<li>Labels may contain numbers, but will not start with them. A label
may be <i>used</i> before it is defined.
</ul>