Initial import of Red Planet v4.10 Win32 source

Imports the current Win32 source for the pod-racing game 'Red Planet',
built on the MUNGA engine and its L4 (Win32/DirectX) platform layer:

- MUNGA / MUNGA_L4: cross-platform engine core and Win32 backend
- RP / RP_L4: Red Planet game logic and Win32 application
- DivLoader, Setup1: asset loader and installer project
- lib, MUNGA_L4/openal, MUNGA_L4/sos: third-party audio dependencies

Removed stale Subversion metadata and added .gitignore/.gitattributes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

MUNGA_L4/L4KEYBD.cpp

@@ -0,0 +1,24 @@
+#include "mungal4.h"
+#pragma hdrstop
+
+#include <iostream>
+#include <conio.h>
+
+int PC_Keyboard_Read(void)
+{
+	int	c;
+
+	if (!kbhit())		// if keyboard has not been hit, return zero
+	{
+		return(0);
+	}
+	else
+	{
+		c = getch();	// keyboard was hit, get code	
+		if (c == 0)		// zero: next character is extended code
+		{
+			c = getch() | 0x0100;	// flag as extended
+		}
+		return(c);		// return the value
+	}
+}