Merged SDL2 changes from bartbes/love-experiments/SDL2 into default.

- Added love.system module, including clipboard functions.

- Added custom hardware cursors (love.mouse.newCursor, love.mouse.setCursor.)

- Revamped love.joystick:
-- added Joystick objects and moved love.joystick functions which operated on individual joysticks to methods on the Joystick objects.
-- Added love.joystick.getJoystick and love.joystick.getJoystickCount.
-- Added events for when joysticks are connected and disconnected.
-- Added 'Gamepad' methods to Joystick objects: Joystick:isGamepad, Joystick:getGamepadAxis, and Joystick:isGamepadDown. They're a common abstraction for xbox controller-like joystick across operating systems.

- Added monitor choosing support and "fullscreen desktop" mode to love.window.

- Moved unicode text input events to their own callback function (love.textinput), removed the key repeat functions from love.keyboard and made the second argument of love.keypressed a boolean saying whether the keypress was a repeat.

- liblove now works with love.window and love.graphics in OS X

src/modules/system/System.cpp

@@ -0,0 +1,63 @@
+/**
+ * Copyright (c) 2006-2013 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+#include "System.h"
+
+namespace love
+{
+namespace system
+{
+
+std::string System::getOS() const
+{
+#ifdef LOVE_MACOSX
+	return "OS X";
+#elif LOVE_WINDOWS
+	return "Windows";
+#elif LOVE_LINUX
+	return "Linux";
+#else
+	return "Unknown";
+#endif
+}
+
+bool System::getConstant(const char *in, System::PowerState &out)
+{
+	return powerStates.find(in, out);
+}
+
+bool System::getConstant(System::PowerState in, const char *&out)
+{
+	return powerStates.find(in, out);
+}
+
+StringMap<System::PowerState, System::POWER_MAX_ENUM>::Entry System::powerEntries[] =
+{
+	{"unknown", System::POWER_UNKNOWN},
+	{"battery", System::POWER_BATTERY},
+	{"nobattery", System::POWER_NO_BATTERY},
+	{"charging", System::POWER_CHARGING},
+	{"charged", System::POWER_CHARGED},
+};
+
+StringMap<System::PowerState, System::POWER_MAX_ENUM> System::powerStates(System::powerEntries, sizeof(System::powerEntries));
+
+} // system
+} // love