Improve debugging functions

- More sensible stack tracer, in C++ (no symbols yet)
- Was forgetting to add null frame to new kernel stacks
- __kernel_assert was using an old vector
- A GP fault will only print its associated table entry

src/kernel/debug.s

@@ -18,19 +18,3 @@ _halt:
 	hlt
 	jmp _halt
 
-
-global get_frame
-get_frame:
-	mov rcx, rbp
-
-.loop:
-	mov rax, [rcx + 8]
-	mov rcx, [rcx]
-	cmp rdi, 0
-	je .done
-
-	sub rdi, 1
-	jmp .loop
-
-.done:
-	ret