Implemented 'walk process' and 'walk threads' commands using toolhelp
snapshots.

debugger/debugger.h

diff --git a/debugger/debugger.h b/debugger/debugger.h
index 2ff273c..24d3bb4 100644
--- a/debugger/debugger.h
+++ b/debugger/debugger.h
@@ -320,6 +320,7 @@
 extern void DEBUG_DumpModule(DWORD mod);
 extern void DEBUG_WalkModules(void);
 extern void DEBUG_WalkProcess(void);
+extern void DEBUG_WalkThreads(void);
 extern void DEBUG_DumpQueue(DWORD q);
 extern void DEBUG_WalkQueues(void);
 extern void DEBUG_InfoSegments(DWORD s, int v);