binary reads

Right now GDB's remote protocol supports binary writes

    X<addr>,<length>:XX...

There is a desire internally for binary reads to speed up the reading of large structures.

I'm not convinced that there is a need; but we do have some *large* structures.
And it would cut in half the number of round trips needed to read them.

My thinking was, since there is no 'x' packet, how about:

    x<addr>,<length>

with possible responses of

    XXXX.... -- the data requested, escaped as for other binary data
    E NN -- an error occurred
    '' -- an empty packet -- means, as now, packet not supported.

Thoughts?

David