New version of phylomorphospace with user control of x & y limits (and other things)

A phytools user today requested user control of x and y limits in phylomorphospace. Currently phylomorphospace sets xlim and ylim based on the range of tip and ancestral values for x & y and this can't be adjusted. It is straightforward to migrate control of this to the user, and I've done this through the "three-dot argument" (i.e., ...). I've also added user control of xlab and ylab, as well as fsize to control the font size of tip labels. fsize is relative to the default font size of textxy(...,cx=0.75).

Code for the new version of phylomorphospace is here, but because the function calls textxy in the 'calibrate' package internally, and phytools imports from calibrate, users will need to either load calibrate to run phylomorphospace from source, or they can install the newest minor build of phytools (phytools 0.2-24).

Here's a quick demo:

> require(phytools)
Loading required package: phytools
...
> packageVersion("phytools")
[1] ‘0.2.24’
> tree<-pbtree(n=30)
> XX<-fastBM(tree,nsim=2)
> par(mar=c(5.1,4.1,2.1,2.1))
> phylomorphospace(tree,XX) # default

> phylomorphospace(tree,XX,ylim=c(-3,4),xlim=c(-4.5,3.5), ylab="trait 1",xlab="trait 2")

That's it.