Hi,
thank you for feedback. We will add this datatype to next version.
As temporary solution you can add this datatype to Skipper configuration file by yourself.
Simply open file Doctrine2.skipper.cfg.xml located in SkipperDirectory/Configurations/Frameworks and add following code to line 205 (inside data-types element)
<data-type name="dateinterval"/>
This will tell Skipper about new datatype.