CodeGenMonad: add Functor instance

codegen: also set execute permissions for large codebuffers

a follow up from commit 5630bf33a46d9bf4

disasm: also label bad instructions

before:
0ad40017  ff 34 24                      push   dword ptr [esp]
0ad4001a  ff ff                         (invalid opcode, byte=255)
0ad4001c  90                            nop

after:
0a2f5017  ff 34 24                      pushl  (%esp)
0a2f501a                          jvm_insn: INVOKESPECIAL 3: [0a2f501a]
0a2f501a                          java/lang/NullPointerException.<init>.()
returns Void: [0a2f501a]
0a2f501a  ff ff                         (invalid opcode, byte=255)
0a2f501c  90                            nop

upstream: update to 0.5.0.0

switched harpy to disassembler-0.1.0.99 (git@wien.tomnetworks.com:disassembler.git, hapry is now 0.4.3.99

codegen: explicit allocate codebuffer with proper permissions

we had weird issues, when upgrading ghc:
http://stackoverflow.com/questions/10341943/ghc-segmentation-fault-under-strange-conditions

therefore, this fix: use `mprotect' to set the codebuffer explicitly executable.
`mprotect' requires aligned memory, so we use `memalign'.

monadIO: export Control.Monad.Trans too

I know, it's hackish. but otherwise, the instantiation
of CodeGen in MonadIO isn't visible o_O

upgrading to ghc 7.4.1

$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 7.4.1

Initial commit: 0.4.3.0 from hackage