Split the two command implementations into separate libraries (#2012)

This will allow us at the user code side to determine to include old commands, new commands or both.

wpilibNewCommands/src/main/native/cpp/frc2/command/ParallelRaceGroup.cpp

@@ -0,0 +1,69 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. 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 "frc2/command/ParallelRaceGroup.h"
+
+using namespace frc2;
+
+ParallelRaceGroup::ParallelRaceGroup(
+    std::vector<std::unique_ptr<Command>>&& commands) {
+  AddCommands(std::move(commands));
+}
+
+void ParallelRaceGroup::Initialize() {
+  for (auto& commandRunning : m_commands) {
+    commandRunning->Initialize();
+  }
+  isRunning = true;
+}
+
+void ParallelRaceGroup::Execute() {
+  for (auto& commandRunning : m_commands) {
+    commandRunning->Execute();
+    if (commandRunning->IsFinished()) {
+      m_finished = true;
+    }
+  }
+}
+
+void ParallelRaceGroup::End(bool interrupted) {
+  for (auto& commandRunning : m_commands) {
+    commandRunning->End(!commandRunning->IsFinished());
+  }
+  isRunning = false;
+}
+
+bool ParallelRaceGroup::IsFinished() { return m_finished; }
+
+bool ParallelRaceGroup::RunsWhenDisabled() const { return m_runWhenDisabled; }
+
+void ParallelRaceGroup::AddCommands(
+    std::vector<std::unique_ptr<Command>>&& commands) {
+  if (!RequireUngrouped(commands)) {
+    return;
+  }
+
+  if (isRunning) {
+    wpi_setWPIErrorWithContext(CommandIllegalUse,
+                               "Commands cannot be added to a CommandGroup "
+                               "while the group is running");
+  }
+
+  for (auto&& command : commands) {
+    if (RequirementsDisjoint(this, command.get())) {
+      command->SetGrouped(true);
+      AddRequirements(command->GetRequirements());
+      m_runWhenDisabled &= command->RunsWhenDisabled();
+      m_commands.emplace(std::move(command));
+    } else {
+      wpi_setWPIErrorWithContext(CommandIllegalUse,
+                                 "Multiple commands in a parallel group cannot "
+                                 "require the same subsystems");
+      return;
+    }
+  }
+}