Does anyone know how to put a gap between the axes and data in PGFPlots? Essentially I'm looking to use Jean-Luc Doumont's style from his excellent book Trees, Maps, and Theorems. Figure here is from http://www.treesmapsandtheorems.com/pdfs/TM&Th-4.0-summary.pdf. 
Don't worry about the arrows and everything, that is all straightforward. I am specifically asking about the axes position.
