Address IntelliJ warnings

This commit addresses a large number of IntelliJ warnings
that have been left hanging around for far too long.

src/main/java/com/loomcom/symon/devices/Acia6850.java

@@ -31,7 +31,7 @@ import com.loomcom.symon.exceptions.MemoryRangeException;
 /**
  * This is a simulation of the Motorola 6850 ACIA, with limited
  * functionality.
- *
+ * <p>
  * Unlike a 16550 UART, the 6850 ACIA has only one-byte transmit and
  * receive buffers. It is the programmer's responsibility to check the
  * status (full or empty) for transmit and receive buffers before