mosaicplot enhancements (PR#2023)

### Changes by W. Fischer and U. Ligges:
## - Deparsing x in for main title. New arguments: sub, las, cex.axis

function(x, main = deparse(substitute(x)), sub = NULL, xlab = NULL, 
         ylab = NULL, sort = NULL, off = NULL, dir = NULL, 
         color = FALSE, shade = FALSE, margin = NULL, 
         cex.axis = 0.66, las = par("las"), 

    mosaic.cell <- function(X, x1, y1, x2, y2, srt.x, srt.y, 
            adj.x, adj.y, off, dir, color, lablevx, lablevy,
            maxdim, currlev, label)

                     srt=srt.x, adj=adj.x, cex=cex.axis, this.lab)

                     srt=srt.y, adj=adj.y, cex=cex.axis, this.lab)

    ## Calculate string rotation for different settings of las:
    srt.x <- if(las > 1) 90 else 0
    srt.y <- if(las == 0 || las == 3) 90 else 0

             srt = 90, cex = cex.axis)

    if (!is.null(main) || !is.null(xlab) || !is.null(ylab) || !is.null(sub))
        title(main, sub = sub, xlab = xlab, ylab = ylab)
    adj.x <- adj.y <- 0.5
    x1 <- 50; y1 <- 5; x2 <- 950; y2 <- 950
    maxlen.xlabel <- maxlen.ylabel <- 35    
    ## Calculations required for 'las' related string rotation 
    ## and adjustment
    if(srt.x == 90){
        maxlen.xlabel <- 
            max(strwidth(label[[dimd + 1 - match('v', rev(dir))]], 
                cex = cex.axis))
        adj.x <- 1
        y2 <- y2 - maxlen.xlabel
    }
    if(srt.y == 0){
        maxlen.ylabel <- 
            max(strwidth(label[[match('h', dir)]],
                cex = cex.axis))
        adj.y <- 0
        x1 <- x1 + maxlen.ylabel
    }
    
    mosaic.cell(Ind, x1 = x1, y1 = y1, x2 = x2, y2 = y2,
                srt.x = srt.x, srt.y = srt.y, adj.x = adj.x, 
                adj.y = adj.y, off = off / 100, dir = dir, 
                color = color, lablevx = 2, lablevy = 2,
                maxdim = apply(as.matrix(Ind[,1:dimd]), 2, max),
                currlev = 1, label = label)

\method{mosaicplot}{default}(x, main = deparse(substitute(x)), 
                   sub = NULL, xlab = NULL, ylab = NULL,

                   cex.axis = 0.66, las = par("las"),

  \item{sub}{character string for the mosaic sub-title (at bottom).}

  \item{cex.axis}{The magnification to be used for axis annotation,
    defaults to the current multiplied by 0.66.}
  \item{las}{numeric; the style of axis labels, see \code{\link{par}}.}