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/LoggerImpl.cpp

@@ -0,0 +1,77 @@
+/*----------------------------------------------------------------------------*/
+/* 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "LoggerImpl.h"
+
+#include "llvm/Path.h"
+#include "llvm/SmallString.h"
+#include "llvm/StringRef.h"
+#include "llvm/raw_ostream.h"
+
+using namespace nt;
+
+static void DefaultLogger(unsigned int level, const char* file,
+                          unsigned int line, const char* msg) {
+  llvm::SmallString<128> buf;
+  llvm::raw_svector_ostream oss(buf);
+  if (level == 20) {
+    oss << "NT: " << msg << '\n';
+    llvm::errs() << oss.str();
+    return;
+  }
+
+  llvm::StringRef levelmsg;
+  if (level >= 50)
+    levelmsg = "CRITICAL: ";
+  else if (level >= 40)
+    levelmsg = "ERROR: ";
+  else if (level >= 30)
+    levelmsg = "WARNING: ";
+  else
+    return;
+  oss << "NT: " << levelmsg << msg << " (" << file << ':' << line << ")\n";
+  llvm::errs() << oss.str();
+}
+
+LoggerImpl::LoggerImpl(int inst) : m_inst(inst) {}
+
+void LoggerImpl::Start() { DoStart(m_inst); }
+
+unsigned int LoggerImpl::Add(
+    std::function<void(const LogMessage& msg)> callback, unsigned int min_level,
+    unsigned int max_level) {
+  return DoAdd(callback, min_level, max_level);
+}
+
+unsigned int LoggerImpl::AddPolled(unsigned int poller_uid,
+                                   unsigned int min_level,
+                                   unsigned int max_level) {
+  return DoAdd(poller_uid, min_level, max_level);
+}
+
+unsigned int LoggerImpl::GetMinLevel() {
+  auto thr = GetThread();
+  if (!thr) return NT_LOG_INFO;
+  unsigned int level = NT_LOG_INFO;
+  for (size_t i = 0; i < thr->m_listeners.size(); ++i) {
+    const auto& listener = thr->m_listeners[i];
+    if (listener && listener.min_level < level) level = listener.min_level;
+  }
+  return level;
+}
+
+void LoggerImpl::Log(unsigned int level, const char* file, unsigned int line,
+                     const char* msg) {
+  // this is safe because it's null terminated and always the end
+  const char* filename = llvm::sys::path::filename(file).data();
+  {
+    auto thr = GetThread();
+    if (!thr || thr->m_listeners.empty())
+      DefaultLogger(level, filename, line, msg);
+  }
+  Send(UINT_MAX, 0, level, filename, line, msg);
+}