[decompiler] clean up vector detection and add vector float product detection (#638)

* change

* recognize vector float product and update tests

test/decompiler/reference/engine/physics/dynamics-h_REF.gc

@@ -64,5 +64,4 @@
   )
 
 ;; failed to figure out what this is:
-(let ((v0-2 0))
-  )
+0

test/decompiler/reference/engine/physics/trajectory-h_REF.gc

@@ -33,5 +33,4 @@
   )
 
 ;; failed to figure out what this is:
-(let ((v0-2 0))
-  )
+0

test/decompiler/reference/engine/physics/trajectory_REF.gc

@@ -41,8 +41,7 @@
    (-> obj initial-velocity y)
    (- (/ (- (-> arg1 y) (-> arg0 y)) arg2) (* (* 0.5 arg2) (-> obj gravity)))
    )
-  (let ((v0-2 0))
-   )
+  0
   (none)
   )
 
@@ -55,8 +54,7 @@
   (let ((f0-1 (/ (vector-vector-xz-distance arg1 arg0) arg2)))
    (TODO-RENAME-11 obj arg0 arg1 f0-1 arg3)
    )
-  (let ((v0-2 0))
-   )
+  0
   (none)
   )
 
@@ -77,8 +75,7 @@
     )
    (TODO-RENAME-11 obj arg0 arg1 f0-3 arg3)
    )
-  (let ((v0-1 0))
-   )
+  0
   (none)
   )
 
@@ -97,8 +94,7 @@
     )
    (TODO-RENAME-13 obj arg0 arg1 f0-3 arg3)
    )
-  (let ((v0-1 0))
-   )
+  0
   (none)
   )
 
@@ -128,7 +124,6 @@
      )
     )
    )
-  (let ((v0-2 0))
-   )
+  0
   (none)
   )