[glass] Add more widgets (#2947)

This adds the following widgets:
- Speed Controller
- Gyroscope
- Command
- Subsystem
- PIDController
- Scheduler

glass/src/lib/native/cpp/other/CommandScheduler.cpp

@@ -0,0 +1,41 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2020 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 "glass/other/CommandScheduler.h"
+
+#include <imgui.h>
+
+#include "glass/Context.h"
+#include "glass/DataSource.h"
+
+using namespace glass;
+
+void glass::DisplayCommandScheduler(CommandSchedulerModel* m) {
+  ImGui::SetNextItemWidth(ImGui::GetFontSize() * 20);
+  ImGui::Text("Scheduled Commands: ");
+  ImGui::Separator();
+  ImGui::Spacing();
+
+  if (m->Exists()) {
+    float pos = ImGui::GetContentRegionAvail().x * 0.97f -
+                ImGui::CalcTextSize("Cancel").x;
+
+    const auto& commands = m->GetCurrentCommands();
+    for (size_t i = 0; i < commands.size(); ++i) {
+      ImGui::Text("%s", commands[i].c_str());
+      ImGui::SameLine(pos);
+
+      ImGui::PushID(i);
+      if (ImGui::Button("Cancel")) m->CancelCommand(i);
+      ImGui::PopID();
+    }
+  } else {
+    ImGui::PushStyleColor(ImGuiCol_Text, IM_COL32(96, 96, 96, 255));
+    ImGui::Text("Unknown Scheduler");
+    ImGui::PopStyleColor();
+  }
+}