Improved networking code

Mostly tidying of code that excessively re-calls itself.

Normalized duplicate code in Peer that was used for connecting to
new peer or accepting a connection from another peer.

Added MessageException so different, specific situations in Peer's main
run() thread can be treated differently instead of one, broad catch-all Exception.

Added documentation and reformatted code to "Eclipse" format
but with extra indent on switch "case:" statements.

Network.java still needs work in terms of calling both peer.close() and peer.interrupt().
(Has comments added to this effect).

Qora/src/api/PeersResource.java

@@ -71,7 +71,16 @@ public String addPeer(String address) {
 			throw ApiErrorFactory.getInstance().createError(
 					ApiErrorFactory.ERROR_INVALID_NETWORK_ADDRESS);
 		}
-		peer.addPingCounter();
+		/*
+		 *  XXX what is the purpose of this call?
+		 *  PeerMap.addPeer() tests for peer.pingCounter > 1 but after this call
+		 *  peer.pingCounter will only be 1 so there's no difference code-path-wise
+		 *  between pingCounter being 0 or 1.
+		 *  Also creating a new Peer starts a Pinger thread which will increment pingCounter
+		 *  and call PeerMap.addPeer()
+		 */
+		// was: peer.addPingCounter();
+		// now: peer.onPingSuccess(); which also performs next line:
 		DBSet.getInstance().getPeerMap().addPeer(peer);
 
 		return "OK";
@@ -173,7 +182,7 @@ else if(DBSet.getInstance().getPeerMap().contains(peer.getAddress().getAddress()
 			o.put("version", Controller.getInstance().getVersionOfPeer(peer).getA());
 			o.put("buildTime", DateTimeFormat.timestamptoString(Controller.getInstance().getVersionOfPeer(peer).getB(), "yyyy-MM-dd HH:mm:ss z", "UTC"));
 		}
-		if(peer.isPinger())	{
+		if(peer.hasPinger())	{
 			o.put("ping", peer.getPing());
 		}
 		if(peer.getConnectionTime()>0) {

Qora/src/network/Network.java

@@ -101,7 +101,7 @@ public void onDisconnect(Peer peer) {
 
 		//CLOSE CONNECTION IF STILL ACTIVE
 		peer.close();
-		peer.interrupt();
+		peer.interrupt(); // might be handled inside peer.close()
 
 		//NOTIFY OBSERVERS
 		this.setChanged();