Finish up parser and assembler with more-or-less complete syntax

Major changes inlude:

* Bit the bullet and now instructions have their length hard-coded
* Move from_utf8 object parsing to be done by their objects (instead of
  a Parser god object)
* A list of AST sections are assembled into an Object using the new
  vm::obj::assemble module.
* Changed the object layout some in the spec, and adjusted code to match
  this.

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

test.asm

@@ -1,28 +1,35 @@
-.section data
+data $0x1000 .. $0x2000 {
+}
 
-.section code
+code $0x0 {
+    main:
+        storeimm %r00, $0xDEAD
+        storeimm %r01, $16
 
-main:
-    storeimm %r00, $0xDEAD
-    storeimm %r01, $16
+        shl %r00, %r01
 
-    shl %r00, %r01
+        storeimm %r01, $0xBEEF
+        or %r00, %r01
 
-    storeimm %r01, $0xBEEF
-    or %r00, %r01
+        storeimm %r01, $0xDEADBEEF
 
-    storeimm %r01, $0xDEADBEEF
+        storeimm %r00, failure
+        storeimm %r01, ok
+        cmpeq %r00, %r01
 
-    storeimm %r00, failure
-    storeimm %r01, ok
-    cmpeq %r00, %r01
+        jz %r00
 
-    jz %r00
+        jmp %r01
 
-    jmp %r01
+    failure:
+        storeimm %status, $1
+        halt
 
-failure:
-    storeimm %status, $1
-    halt
+    ok:
 
-ok:
+    .export main
+}
+
+meta {
+    entry: main
+}