summaryPlots.R - Single Individual Fix

[gregpinero]

Confirm that it isn't able to run on only one individual.

Exit gracefully if so with helpful error message.

The error Sarah was seeing:

$ cat msgRun3.16178.err
Error in colMeans(p + p1 - 2 * p * p1, na.rm = na.rm) :
'x' must be an array of at least two dimensions
Calls: est.rf.p.profile -> colMeans
Execution halted