Implement independent instances.

Previously, most of the classes were implemented as singletons so only one
instance was possible.

This change adds an instance handle-based API.  In Java, this API is located
in a different package than the old API (edu.wpi.first.networktables).

Backwards compatibility with ITable and the old NetworkTable API is largely
maintained, but a handful of classes have moved to the new package in Java
(ConnectionInfo and PersistentException), and the old JNI has been completed
replaced.

Also:
- Move SetTeam implementation to Dispatcher.
- Consistently pass time through Java and C++ Value API.
- Rename nt_Value.h to NetworkTableValue.h for consistency with Java.
- Improve documentation
- Make C++ and Java APIs more consistent
- Document RPC functions and support RPC in Java.
- Add polling features for entry and connection listeners and use them to
  move callback threads to Java level.
- Remove thread start and stop hooks (as polling is available).
- Make Notifiers, RpcServer, Dispatcher, and Storage mockable.
- Set NOTIFY_NEW on immediate entry notifications.
- Make GetTable("/") and GetTable("") equivalent.
- Generate local notification for flags update when loading persistent file.

And many unit test updates/changes:
- Use InitGoogleMock instead of InitGoogleTest in test main.
- Move test printers to TestPrinter.h/cpp.
- Provide printers for StringRef, EntryNotifier, and Handle.
- StorageTest: Check notifications.
- Add entry notifier unit tests.
- Storage: Add test for incoming entry assignment.
- Update connection listener tests.
- Add entry listener unit tests.

Fixes #11, #140, #189, #190, #192, #193, #221

src/main/native/cpp/ConnectionNotifier.h

@@ -0,0 +1,73 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2015. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#ifndef NT_CONNECTIONNOTIFIER_H_
+#define NT_CONNECTIONNOTIFIER_H_
+
+#include "ntcore_cpp.h"
+
+#include "CallbackManager.h"
+#include "Handle.h"
+#include "IConnectionNotifier.h"
+
+namespace nt {
+
+namespace impl {
+
+class ConnectionNotifierThread
+    : public CallbackThread<ConnectionNotifierThread, ConnectionNotification> {
+ public:
+  ConnectionNotifierThread(int inst) : m_inst(inst) {}
+
+  bool Matches(const ListenerData& listener,
+               const ConnectionNotification& data) {
+    return true;
+  }
+
+  void SetListener(ConnectionNotification* data, unsigned int listener_uid) {
+    data->listener =
+        Handle(m_inst, listener_uid, Handle::kConnectionListener).handle();
+  }
+
+  void DoCallback(
+      std::function<void(const ConnectionNotification& event)> callback,
+      const ConnectionNotification& data) {
+    callback(data);
+  }
+
+  int m_inst;
+};
+
+}  // namespace impl
+
+class ConnectionNotifier
+    : public IConnectionNotifier,
+      public CallbackManager<ConnectionNotifier,
+                             impl::ConnectionNotifierThread> {
+  friend class ConnectionNotifierTest;
+  friend class CallbackManager<ConnectionNotifier,
+                               impl::ConnectionNotifierThread>;
+
+ public:
+  explicit ConnectionNotifier(int inst);
+
+  void Start();
+
+  unsigned int Add(
+      std::function<void(const ConnectionNotification& event)> callback);
+  unsigned int AddPolled(unsigned int poller_uid);
+
+  void NotifyConnection(bool connected, const ConnectionInfo& conn_info,
+                        unsigned int only_listener = UINT_MAX) override;
+
+ private:
+  int m_inst;
+};
+
+}  // namespace nt
+
+#endif  // NT_CONNECTIONNOTIFIER_H_