abbrevLength
Default = c(0,0). Either a length 2 vector or a named list
to control lengths of factor names and levels in the legend. If a length 2 vector, it
gives the minlength argument for the abbreviate function for abbreviating all
the factor names and their levels, in that order. A value of 0 for either means
"don't abbreviate." For back compatibility, a single numeric y will also be accepted
and changed to c(y,0). If a named list, the names must be those of of the
conditioning factors to abbreviate, and values length 2 vectors as above to
control abbreviation lengths for the corresponding factor names and levels.