Enhance QRF with the mxTuple field, which if greater than 1 causes the

Enhance QRF with the mxTuple field, which if greater than 1 causes the
QRF_STYLE_Insert style to group as many as mxTuple adjacent rows into
a single INSERT statement.  The field is accessible using the -mxtuple
option in the TCL interface, and the --mxtuple option in ".mode".  The
output of the ".dump" and ".fullschema" commands responds to the current
--mxtuple setting.

FossilOrigin-Name: 659ff6ab5580250707908af003ecd093bd5313f03f21f0efd000a7aff6638b3c