keep some processes mapped in always; direct message copying

where possible (no buffering); no more explicit vm checkranges
in kernel; new allocator for vm using avl tree without needing
remapping

kernel/debug.h

@@ -25,9 +25,9 @@
 #define DEBUG_TIME_LOCKS		1
 
 /* Runtime sanity checking. */
-#define DEBUG_VMASSERT			0
-#define DEBUG_SCHED_CHECK		0
-#define DEBUG_STACK_CHECK		0
+#define DEBUG_VMASSERT			1
+#define DEBUG_SCHED_CHECK		1
+#define DEBUG_STACK_CHECK		1
 #define DEBUG_TRACE			1
 
 #if DEBUG_TRACE