Overwrite changes in Word8 explorer with master
parameterise prog_to_bytecode over the instruction length

use real_inst_length for the compiler explorer and for prog_to_x86_64,
otherwise use \x. 0.
commented out broken bits of x64_heap...
move termination proof for inf_type_to_string earlier

unfortunately it still fails to go through the translator for some
reason
fix translation of inf_type_to_string
fix sideTheory on Word8Array
update ml_repl_moduleTheory for Word8Array
delete (presuming unused) oneshotTheory
Use separate calls to remove labels for bytecode and asm pp
start updating bootstrap lemmas for Word8Array

something seems broken about the tags of primitive constructors: the
compiler's environment after the bootstrap doesn't match up with the
tags from conLang.
Merge remote-tracking branch 'origin/master' into Word8Array
Merge branch 'Word8Array'

Bootstrap builds. Compiler Explorer is broken. x86-64 is substantially
commented out. The explorer should be fixed shortly.
Merge remote-tracking branch 'origin/master' into init_env

Conflicts:
	explorer/pp/astPP.sml