Rename 'Standard Gaming Platform' to 'sgp' (#246)

* rename 'Standard Gaming Platform' to 'sgp'

* Adapt CMakeLists.txt files to renamed SGP directory

* Lowercase it

sgp/timer.cpp

@@ -0,0 +1,63 @@
+	#include "types.h"
+	#include <windows.h>
+		#include "video.h"
+	#include "timer.h"
+
+#ifndef WIN32_LEAN_AND_MEAN
+	#define WIN32_LEAN_AND_MEAN
+#endif
+
+UINT32 guiStartupTime;
+UINT32 guiCurrentTime;
+
+void CALLBACK Clock( HWND hWindow, UINT uMessage, UINT idEvent, DWORD dwTime )
+{
+	guiCurrentTime = GetTickCount();
+	if (guiCurrentTime < guiStartupTime)
+	{ // Adjust guiCurrentTime because of loopback on the timer value
+	guiCurrentTime = guiCurrentTime + (0xffffffff - guiStartupTime);
+	}
+	else
+	{ // Adjust guiCurrentTime because of loopback on the timer value
+	guiCurrentTime = guiCurrentTime - guiStartupTime;
+	}
+}
+
+BOOLEAN InitializeClockManager(void)
+{
+
+	// Register the start time (use WIN95 API call)
+	guiCurrentTime = guiStartupTime = GetTickCount();
+	SetTimer(ghWindow, MAIN_TIMER_ID, 10, (TIMERPROC)Clock);
+
+
+	return TRUE;
+}
+
+void	ShutdownClockManager(void)
+{
+
+	// Make sure we kill the timer
+	KillTimer(ghWindow, MAIN_TIMER_ID);
+
+}
+
+TIMER	GetClock(void)
+{
+	return guiCurrentTime;
+}
+
+TIMER	SetCountdownClock(UINT32 uiTimeToElapse)
+{
+	return (guiCurrentTime + uiTimeToElapse);
+}
+
+UINT32 ClockIsTicking(TIMER uiTimer)
+{
+	if (uiTimer > guiCurrentTime)
+	{ // Well timer still hasn't elapsed
+	return (uiTimer - guiCurrentTime);
+	}
+	// Time's up
+	return 0;
+}