This generates a matrix of branching times that can be used with
fitdAICrc.batch under any parameterization of a general birth-death
model with or without incomplete sampling.
To simulate a clade with incomplete sampling, note that CladeSize is
the true size of a phylogeny, and NumberMissing is the number of missing taxa,
so if you specified CladeSize = 100 and NumberMissing = 20, your resulting
trees would have 80 tips (Trees with 100 tips would be simulated, but then 20 taxa
would be dropped randomly to simulate incomplete sampling).
THis function is basically a wrapper for the birthdeath.tree function
from Geiger, but makes it more amenable to calculation of the delta AIC test
statistic for detecting temporal changes in diversification rates.
Value
an n x m matrix of branching times, where n is size CladeSize - NumberMissing
and m is size NumberOfReps .
providing 
.