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/WireDecoder.h

@@ -10,10 +10,10 @@
 
 #include <cstddef>
 
-#include "nt_Value.h"
+#include "networktables/NetworkTableValue.h"
 #include "support/leb128.h"
 #include "support/raw_istream.h"
-//#include "Log.h"
+#include "Log.h"
 
 namespace nt {
 
@@ -26,7 +26,8 @@ namespace nt {
  */
 class WireDecoder {
  public:
-  explicit WireDecoder(wpi::raw_istream& is, unsigned int proto_rev);
+  WireDecoder(wpi::raw_istream& is, unsigned int proto_rev,
+              wpi::Logger& logger);
   ~WireDecoder();
 
   void set_proto_rev(unsigned int proto_rev) { m_proto_rev = proto_rev; }
@@ -34,6 +35,9 @@ class WireDecoder {
   /* Get the active protocol revision. */
   unsigned int proto_rev() const { return m_proto_rev; }
 
+  /* Get the logger. */
+  wpi::Logger& logger() const { return m_logger; }
+
   /* Clears error indicator. */
   void Reset() { m_error = nullptr; }
 
@@ -54,8 +58,7 @@ class WireDecoder {
     *buf = m_buf;
     m_is.read(m_buf, len);
 #if 0
-    nt::Logger& logger = nt::Logger::GetInstance();
-    if (logger.min_level() <= NT_LOG_DEBUG4 && logger.HasLogger()) {
+    if (m_logger.min_level() <= NT_LOG_DEBUG4 && m_logger.HasLogger()) {
       std::ostringstream oss;
       oss << "read " << len << " bytes:" << std::hex;
       if (!rv)
@@ -64,7 +67,7 @@ class WireDecoder {
         for (std::size_t i=0; i < len; ++i)
           oss << ' ' << (unsigned int)((*buf)[i]);
       }
-      logger.Log(NT_LOG_DEBUG4, __FILE__, __LINE__, oss.str().c_str());
+      m_logger.Log(NT_LOG_DEBUG4, __FILE__, __LINE__, oss.str().c_str());
     }
 #endif
     return !m_is.has_error();
@@ -135,6 +138,9 @@ class WireDecoder {
   /* input stream */
   wpi::raw_istream& m_is;
 
+  /* logger */
+  wpi::Logger& m_logger;
+
   /* temporary buffer */
   char* m_buf;