Changes in version 2.1.2 (2014-04-29)

New features or changed behaviour of old functions

    o   validate() function to set out-of-range values to NA
    o   min, max as fields in summary.selectedstatistics
    o   secrdesign.pdf vignette
    o   header in summary output now includes pop.args
    o   run.scenarios() allows IHP population simulation as 
        alternative to specifying uniform density

Bugs fixed

    o   maskset was not saved when specified in run.scenarios()
