Simulator is just about ready for real-world testing now. Added a simulated

MOS6551 ACIA at address $C000 which does buffered input and output via the
console. Updated the README with a bit more documentation, and bumped the
version number to 0.1 because I'm impatient.

src/main/java/com/loomcom/symon/exceptions/FifoUnderrunException.java

@@ -0,0 +1,7 @@
+package com.loomcom.symon.exceptions;
+
+public class FifoUnderrunException extends Exception {
+  public FifoUnderrunException(String msg) {
+    super(msg);
+  }
+}