dsm news!

# 2.1.3
  * CRAN-compatibility fixes


# 2.1.2
  * updates to dsm.cor
  * more unified plotting
  * variance estimation tweaks for non-dsm models

# 2.0.6

  * removed warning about if() comparison length in make.soapgrid need to pass bnd as a list()
  * dsm.cor now handles gamm objects
  * dsm.cor allows one to check residual autocorrelation in your models
  * presence/absence data now no longer needs a dummy detection function object

# 2.0.5

  * started NEWS file
  * fixed bug where dsm.var.gam() didn't return predictions so plotting the result would fail
  * silly typo in docs
  * check if we're using mgcv version >= 1.7-24 for GAMM fitting and warn if not

