Kernel: Rewrite ProcFS.

Now the filesystem is generated on-the-fly instead of manually adding and
removing inodes as processes spawn and die.

The code is convoluted and bloated as I wrote it while sleepless. However,
it's still vastly better than the old ProcFS, so I'm committing it.

I also added /proc/PID/fd/N symlinks for each of a process's open fd's.

Kernel/init.cpp

@@ -16,7 +16,7 @@
 #include <Kernel/VirtualFileSystem.h>
 #include "GUIEventDevice.h"
 #include "MemoryManager.h"
-#include "ProcFileSystem.h"
+#include "ProcFS.h"
 #include "RTC.h"
 #include "VirtualConsole.h"
 #include "Scheduler.h"
@@ -171,8 +171,8 @@ void init()
 
     memset(&system, 0, sizeof(system));
 
-    auto procfs = ProcFS::create();
-    procfs->initialize();
+    auto new_procfs = ProcFS::create();
+    new_procfs->initialize();
 
     auto devptsfs = DevPtsFS::create();
     devptsfs->initialize();