XY2-200(4MHz), Z channel, STATUS channel support

[Spirit532]

Here's a few suggestions:
1 - It would be nice to have support for the faster XY2-200 interface - it's absolutely identical, except that it's clocked at 4MHz instead of 2MHz. Just a switch between clock speeds should be sufficient.
2 - Add support for the Z(usually the focus) channel for 3-axis scanheads. This might be an issue, since the Frame class only has mData1 and mData2, which you're already using, and there's no mData3 to fit Z in.
3 - Add support for status channel decoding, which is handy for seeing what the scanhead is doing, and most of them support it.
4 - There's also the XY2-(1/2)00 -E protocol, which could be handy to have support for, but I've never really seen an -E device out in the wild that actually used the features.

I briefly attempted to add support for Z, but ran into the mData3 issue and didn't delve to deep into workarounds.