The `_SimpleT2Decompiler.execute` method expects that handlers for
hintmask/cntrmask operators return a tuple of (hintMaskBytes, index).
The index value is used to skip to the next token following the
hintmask bytes.
However, the `_DehintingT2Decompiler.op_hintmask` method was returning
None, thus the hintmask bytes were evaluated as the following token
instead of being consumed as such; but since in legacy python 2
`isinstance(token, basestring)` is True for both operators and
hintmask bytes, the latter might sometimes be wrongly interpreted
as operators!
For example, the hintmask bits '0110111101110010', encoded as a
bytes string `'\x6f\x72'` was being confused for the unimplemented
`'or'` operator...
Fixes#1006