Add storeimm32 and storeimm64 syntax

These explicitly allow usage of storeimm32 and storeimm64 in the
assembler syntax. It will also warn you if you try to store a value
that's too large using the storeimm32 instruction

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

test.asm

@@ -1,25 +1,25 @@
 code $0x0 {
     main:
-        storeimm %r00, $0xDEAD
-        storeimm %r01, $16
+        storeimm32 %r00, $0xDEAD
+        storeimm64 %r01, $16
 
         shl %r00, %r01
 
-        storeimm %r01, $0xBEEF
+        storeimm32 %r01, $0xBEEF
         or %r00, %r01
 
-        storeimm %r01, $0xDEADBEEF
+        storeimm64 %r01, $0xDEADBEEF
 
         cmpeq %r00, %r01
-        storeimm %r00, failure
-        storeimm %r01, ok
+        storeimm32 %r00, failure
+        storeimm64 %r01, ok
 
         jz %r00
 
         jmp %r01
 
     failure:
-        storeimm %status, $1
+        storeimm32 %status, $1
 
     ok: halt