[Decompiler] WIP: Stack Spills (#382)

* set up types

* cleaned up type analysis and got things working through atomic ops

* expression working, need types

* improved types and names

* getting close

* finish up dma-disasm

* fix

test/decompiler/reference/all_forward_declarations.gc

@@ -3,6 +3,7 @@
 (define-extern fact (function int int))
 (define-extern max (function int int int))
 (define-extern min (function int int int))
+(define-extern valid? (function object type basic basic object symbol))
 
 ;; KERNEL
 (declare-type process basic)
@@ -82,6 +83,10 @@
   '(none)
   )
 
+(defmacro empty-form ()
+  '(none)
+  )
+
 
 ;; math
 (define-extern fabs (function float float))
@@ -172,6 +177,7 @@
     (unpack-v4-16 109)
     (unpack-v4-8  110)
     (unpack-v4-5  111)
+    (cmd-mask     239)
     )
 
 (defenum vif-cmd-32