C++ refactoring, plus low-power support, plus software-based SPI CS

I'm backlogged.

LowPowerDelay.h

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2019  Max Regan
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#pragma once
+
+#include "Task.h"
+#include "LowPower.h"
+
+class LowPowerDelay : public Common::Schedule::Task {
+
+public:
+    LowPowerDelay()
+        : m_is_first(true)
+    {}
+    Common::Schedule::NextTime execute() {
+
+        if (m_is_first) {
+            m_is_first = false;
+        } else {
+            BSP::LowPower::stop();
+        }
+
+        return Common::Schedule::NextTime::in(Common::Time::millis(200));
+    }
+
+private:
+    bool m_is_first;
+};