Implement receiver HID++ connect/disconnect events

Many changes were made here but that was the biggest one.

There's currently a bug where std::system_error: Broken pipe is thrown
after launching the daemon with a receiver connector.

A workaround for this bug is to simply shake the mouse while starting
the daemon. I will investigate this soon.

src/logid/Receiver.cpp

@@ -1,9 +1,50 @@
+#include <cassert>
 #include "Receiver.h"
 #include "util.h"
+#include "backend/hidpp10/Error.h"
+#include "backend/hidpp20/Error.h"
 
 using namespace logid;
+using namespace logid::backend;
 
-Receiver::Receiver(std::string path) : _path (path)
+Receiver::Receiver(std::string path) : dj::ReceiverMonitor(path)
 {
     log_printf(DEBUG, "logid::Receiver created on %s", path.c_str());
+}
+
+void Receiver::addDevice(hidpp::DeviceConnectionEvent event)
+{
+    try {
+        if(!event.linkEstablished)
+            return; // Device is probably asleep, wait until it wakes up
+
+        hidpp::Device hidpp_device(receiver(), event);
+
+        auto version = hidpp_device.version();
+
+        if(std::get<0>(version) < 2) {
+            log_printf(INFO, "Unsupported HID++ 1.0 device on %s:%d connected.",
+                    _path.c_str(), event.index);
+            return;
+        }
+
+        std::shared_ptr<Device> device = std::make_shared<Device>(
+                receiver()->rawDevice(), event.index);
+
+        assert(_devices.find(event.index) == _devices.end());
+
+        _devices.emplace(event.index, device);
+
+    } catch(hidpp10::Error &e) {
+        log_printf(ERROR, "Caught HID++ 1.0 error while trying to initialize "
+                          "%s:%d: %s", _path.c_str(), event.index, e.what());
+    } catch(hidpp20::Error &e) {
+        log_printf(ERROR, "Caught HID++ 2.0 error while trying to initialize "
+                          "%s:%d: %s", _path.c_str(), event.index, e.what());
+    }
+}
+
+void Receiver::removeDevice(hidpp::DeviceIndex index)
+{
+    _devices.erase(index);
 }