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/Value.cpp

@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "nt_Value.h"
+#include "networktables/NetworkTableValue.h"
 #include "Value_internal.h"
 #include "support/timestamp.h"
 
@@ -16,9 +16,12 @@ Value::Value() {
   m_val.last_change = wpi::Now();
 }
 
-Value::Value(NT_Type type, const private_init&) {
+Value::Value(NT_Type type, unsigned long long time, const private_init&) {
   m_val.type = type;
-  m_val.last_change = wpi::Now();
+  if (time == 0)
+    m_val.last_change = wpi::Now();
+  else
+    m_val.last_change = time;
   if (m_val.type == NT_BOOLEAN_ARRAY)
     m_val.data.arr_boolean.arr = nullptr;
   else if (m_val.type == NT_DOUBLE_ARRAY)
@@ -36,16 +39,18 @@ Value::~Value() {
     delete[] m_val.data.arr_string.arr;
 }
 
-std::shared_ptr<Value> Value::MakeBooleanArray(llvm::ArrayRef<int> value) {
-  auto val = std::make_shared<Value>(NT_BOOLEAN_ARRAY, private_init());
+std::shared_ptr<Value> Value::MakeBooleanArray(llvm::ArrayRef<int> value,
+                                               unsigned long long time) {
+  auto val = std::make_shared<Value>(NT_BOOLEAN_ARRAY, time, private_init());
   val->m_val.data.arr_boolean.arr = new int[value.size()];
   val->m_val.data.arr_boolean.size = value.size();
   std::copy(value.begin(), value.end(), val->m_val.data.arr_boolean.arr);
   return val;
 }
 
-std::shared_ptr<Value> Value::MakeDoubleArray(llvm::ArrayRef<double> value) {
-  auto val = std::make_shared<Value>(NT_DOUBLE_ARRAY, private_init());
+std::shared_ptr<Value> Value::MakeDoubleArray(llvm::ArrayRef<double> value,
+                                              unsigned long long time) {
+  auto val = std::make_shared<Value>(NT_DOUBLE_ARRAY, time, private_init());
   val->m_val.data.arr_double.arr = new double[value.size()];
   val->m_val.data.arr_double.size = value.size();
   std::copy(value.begin(), value.end(), val->m_val.data.arr_double.arr);
@@ -53,8 +58,8 @@ std::shared_ptr<Value> Value::MakeDoubleArray(llvm::ArrayRef<double> value) {
 }
 
 std::shared_ptr<Value> Value::MakeStringArray(
-    llvm::ArrayRef<std::string> value) {
-  auto val = std::make_shared<Value>(NT_STRING_ARRAY, private_init());
+    llvm::ArrayRef<std::string> value, unsigned long long time) {
+  auto val = std::make_shared<Value>(NT_STRING_ARRAY, time, private_init());
   val->m_string_array = value;
   // point NT_Value to the contents in the vector.
   val->m_val.data.arr_string.arr = new NT_String[value.size()];
@@ -67,8 +72,8 @@ std::shared_ptr<Value> Value::MakeStringArray(
 }
 
 std::shared_ptr<Value> Value::MakeStringArray(
-    std::vector<std::string>&& value) {
-  auto val = std::make_shared<Value>(NT_STRING_ARRAY, private_init());
+    std::vector<std::string>&& value, unsigned long long time) {
+  auto val = std::make_shared<Value>(NT_STRING_ARRAY, time, private_init());
   val->m_string_array = std::move(value);
   value.clear();
   // point NT_Value to the contents in the vector.