clearing reg_rrr and reg_mmm more efficiently is an extremely small win,
but a win

read_imm_signed generally should inline well and runs afoul of some
heuristic. inlining gets about 8% improved throughput on the
(unrealistic) in-repo benchmark

it would be great to be able to avoid bounds checks somehow; it looks
like they alone are another ~10% of decode time. i'm not sure how to
pull that off while retaining the generic iterator parameter. might just
not be possible.

* `mwaitx`, `monitorx`, `rdpru`, and `clzero` are now supported
* swapgs is no longer decoded in protected mode
* rdpkru and wrpkru are no longer decoded if mod bits != 11

for memory operands with a base, index, and displacement either
the wrong base would be selected (register number ignored, so only
`*ax` or `r8*` would be reported), or yaxpeax-x86 would report a
base register is present when it is not (`RegIndexBaseScaleDisp`
when the operand is actually `RegScaleDisp`)

thank you to Evan Johnson for catching and reporting this bug!

also bump crate version to 0.1.4 as this will be immediately tagged and
released.

also bump to 0.1.1

add doc comments for public items, record changelog, and lets ship this!!

`OperandCode` (obviously) wildly varies depending on how i feel on a
given week, so it's now hidden to avoid people depending on numerical
values of its discriminants.

`RegisterBank` got a similar treatment with a new `RegisterClass` struct
that's suitable for public use.