Add SteamController implementation

This adds a Steam Shortcuts, Desktop Mode, and X360 Emulation
- Supports all Steam Shortcuts (including on-screen keyboard, and brightness)
- Supports Desktop mode (with a scroll on left pad and left stick), and trackpoint (on right stick)
- Supports X360 mode: hold Options for 1s to switch between Desktop and X360
- Holding Steam button enables Desktop like controls and stops passing all inputs to X360

SteamController/Devices/SteamControllerLizard.cs

@@ -0,0 +1,73 @@
+using hidapi;
+using PowerControl.External;
+using static CommonHelpers.Log;
+
+namespace SteamController.Devices
+{
+    public partial class SteamController
+    {
+        public const int LizardModeUpdateInterval = 250;
+
+        public bool LizardMouse { get; set; } = true;
+        public bool LizardButtons { get; set; } = true;
+
+        private bool? savedLizardMouse;
+        private bool? savedLizardButtons;
+        private DateTime lizardMouseUpdated = DateTime.Now;
+        private DateTime lizardButtonUpdated = DateTime.Now;
+
+        private void UpdateLizardMouse()
+        {
+            if (savedLizardMouse == LizardMouse)
+            {
+                // We need to explicitly disable lizard every some time
+                // but don't fight enabling it, as someone else might be taking control (Steam?)
+                if (LizardMouse || lizardMouseUpdated.AddMilliseconds(LizardModeUpdateInterval) > DateTime.Now)
+                    return;
+            }
+
+            if (LizardMouse)
+            {
+                //Enable mouse emulation
+                byte[] data = new byte[] { 0x8e, 0x00 };
+                neptuneDevice.RequestFeatureReport(data);
+            }
+            else
+            {
+                //Disable mouse emulation
+                byte[] data = new byte[] { 0x87, 0x03, 0x08, 0x07 };
+                neptuneDevice.RequestFeatureReport(data);
+            }
+
+            savedLizardMouse = LizardMouse;
+            lizardMouseUpdated = DateTime.Now;
+        }
+
+        private void UpdateLizardButtons()
+        {
+            if (savedLizardButtons == LizardButtons)
+            {
+                // We need to explicitly disable lizard every some time
+                // but don't fight enabling it, as someone else might be taking control (Steam?)
+                if (LizardButtons || lizardButtonUpdated.AddMilliseconds(LizardModeUpdateInterval) > DateTime.Now)
+                    return;
+            }
+
+            if (LizardButtons)
+            {
+                //Enable keyboard/mouse button emulation
+                byte[] data = new byte[] { 0x85, 0x00 };
+                neptuneDevice.RequestFeatureReport(data);
+            }
+            else
+            {
+                //Disable keyboard/mouse button emulation
+                byte[] data = new byte[] { 0x81, 0x00 };
+                neptuneDevice.RequestFeatureReport(data);
+            }
+
+            savedLizardButtons = LizardButtons;
+            lizardButtonUpdated = DateTime.Now;
+        }
+    }
+}