Update/add instructions in parser

* StoreImm just uses a u64 instead of u32 - we'll figure out the layout
  later
* Jmp implementation added (can't believe I forgot this)
* Add Inst AST item, whose immediates don't have to be a u64 right away

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

test.asm

@@ -2,22 +2,27 @@
 
 .section code
 
-storeimm %r0, $0xDEAD
-storeimm %r1, $16
+main:
+    storeimm %r00, $0xDEAD
+    storeimm %r01, $16
 
-shl %r0, %r1
+    shl %r00, %r01
 
-storeimm %r1, $0xBEEF
-or %r0, %r1
+    storeimm %r01, $0xBEEF
+    or %r00, %r01
 
-storeimm %r1, $0xDEADBEEF
-cmpeq %r0, %r1
-jz failure
+    storeimm %r01, $0xDEADBEEF
 
-jmp ok
+    storeimm %r00, failure
+    storeimm %r01, ok
+    cmpeq %r00, %r01
+
+    jz %r00
+
+    jmp %r01
 
 failure:
-storeimm %status, $1
-halt
+    storeimm %status, $1
+    halt
 
 ok: